The Effects of the Minimum Legal Drinking Age on Traffic Fatalities: An International Comparison between the United States and Canada

Transcription

1 The Effects of the Minimum Legal Drinking Age on Traffic Fatalities: An International Comparison between the United States and Canada Abstract: This paper analyzes the impact of the U.S National Minimum Drinking Age Act on the rate of alcohol-related traffic deaths by comparing traffic fatality rates in the U.S and Canada. The results show that both countries experienced substantial decreases in traffic fatalities and alcohol-related crashes since The data is broken down by the age of the drivers involved to note any specific changes in teen and young adult fatality rates. The similar age specific data of the U.S. and Canada implies that the change in MLDA law can only account for a small part of the decrease in fatality rates. Christine Cusick Economic Honors Thesis May 2006 Acknowledgments: I would like to thank my advisor, Professor David Lee, for his guidance on this project and Professor Roger Craine for his help in Economics H195A. I am also grateful for my friends and family who helped me stay motivated and focused throughout this year.

2 Table of Contents I. Introduction II. Historical Background and Review of the Laws 2.1 U.S. Legislation on MLDA 2.2 Canada Legislation on MLDA 2.3 Other Relevant Laws and Economic Factors III. Literature Review on the Effects of Raising the MLDA 3.1 Raising the MLDA decreases traffic fatalities: The Age effect 3.2 Raising the MLDA shifts traffic fatalities: The Experience effect IV. Approach/ Strategy V. Data Selection 5.1 Sources 5.2 Disadvantages VI. Empirical Results 6.1 Overall Trends 6.2 Alcohol-Related Crashes 6.3 Teen Crashes VII. Conclusion VIII. Bibliography IX. Terms and Definitions 8.1 Terms 8.2 Definitions 1

3 I. Introduction Public awareness of the consequences of driving while under the influence of alcohol has changed public policy and culture. The past three decades have consequently had a dramatic decease in automobile crashes. Despite the progress towards safety in vehicle design, the problem of motor-vehicle crashes is still pertinent; the World Health Organization estimates crashes account for the sixth world-wide leading cause of death. In the U.S., motor vehicle crashes claimed 42,000 lives in 2002; moreover, alcohol was a factor in over 40% of these. 1 Alcohol related crashes, a subset of all motor vehicle accidents, continue to plague society. In 2003, the 17,013 fatalities caused by alcoholrelated vehicle crashes represent an average of one alcohol-related fatality every 31 minutes (NCSA 2004). It is estimated that drinking drivers are at least eight times more likely than sober drivers to cause fatal crashes (Dee and Evans 2001). Clearly, drivers that heavily drink impose negative externalities on society with their increased likelihood of crashes, causing harms to life and property. There are two main strategies that attempt to tax driving while intoxicated in order to make people pay the full social cost of the consequences of alcohol. The first strategy makes use of general deterrence policies which are used to change people s decisions about driving while intoxicated. Examples of these policies include strict punishments, heavy fines, education programs and mass media campaigns. The second strategy aims not at the specific activity of driving intoxicated, but at restricting the availability of alcohol. Alcohol control policies target specific high-risk groups in order to deter alcohol abuse and ultimately drunk driving. 1 Carpenter According to the NCSA, A motor vehicle crash in considered to be alcohol-related if at least one driver or non-occupant (i.e. pedestrian or cyclist) involved in the crash is determined to have had a blood alcohol content (BAC) of 0.01 g/dl or higher 2

4 One policy of this later group is a minimum legal drinking age (MLDA). A lot of drinking and driving literature focus s on the teen driver. As a teen has less experienced both with driving and with drinking, they are a target of many legislation policies to curb drunk driving. Moreover, traffic fatalities are the leading cause of death among people years old in the United States; 34% of all teenage males and 38% of all teenage females who die annually do so because of car crashes. 2 Minimum legal drinking ages attempt to keep alcohol away from minors until they are older and hopefully more likely to be responsible. MLDA laws work by criminalizing the sale or public possession of alcohol to anyone under a certain age. In the United States, the MLDA is 21 years old. This is the highest MLDA in the industrialized world, and was nationally enacted by the National Minimum Drinking Age Act of This paper intends to study the effects of a change in law in the United States by comparing traffic fatalities in the U.S. and Canada to infer what might have happened in the U.S. had there not been a uniform change in the minimum legal drinking age in The 1984 legislation in the U.S. was discrete so we can compare fatalities in the U.S. to values in Canada before and after the law was enacted. The expected results from this observation are that after the law is implemented, alcohol is less accessible to teens in the U.S. and they will have lower traffic fatality rates compared to Canadian teens. Many cross-state studies have been done to analyze the correlation between different MLDA policies and the amount of alcohol related crashes that occur. I review these studies in this paper and try to apply their theories to international data. Fewer studies have been done, however, comparing crashes internationally. I think it is 2 Dee and Evans (2000), Mayhew and Simpson (1999). Take into consideration that years old rarely die of natural causes and tend to be a demographic that takes more risks. 3

5 important to look at the international comparisons to gain a new perspective and distinguish trends on how laws change behaviors. Determining the effectiveness of MLDA laws in deterring drunk driving has multiple benefits to society and individuals. Testing the effects can help policy makers decide where to focus their resources and efforts into reducing traffic fatalities. Although the decision to drive drunk is multifaceted, we can assume using Becker s economic theory of crime that the expected utility of drunk driving can be decreased if the expected penalty and probability of being caught are high (Kenkel 2001). Enforcing MLDA laws would hopefully deter some young people from driving drunk, because of this additional penalty they receive from being underage. Alcohol norms and acceptable drinking habits may vary dramatically by country. Cultural differences are difficult to account for in a statistical study, yet it ought to be pointed out that they serve as a potential factor to skew the results. The following observations assume that there is not a significant difference in cultural views towards drunk driving in the U.S. and Canada. II. Historical Background and Review of the Laws 2.1 U.S. Legislation on MLDA Before the National Minimum Drinking Age Act of 1984, it was up to states to determine their own drinking age legislation. Most states had adopted a MLDA of 21 after the end to Prohibition in the 1920s. The 1970s brought social pressure to reduce the MLDA in accordance with the trend to grant more rights to those who were deemed old enough to be drafted to Vietnam. The Twenty-sixth Amendment lowered the federal 4

6 voting age to 18, so it seemed natural that 18 year olds should by extension deserve the right to participate in other adult activities like drinking. Furthermore, the general sentiment at the time was that alcohol legislation was ineffective in keeping alcohol away from teens in the first place. In 1971, 12 states had an MLDA of 21 and 12 states had an MLDA of By 1977, however, 30 states had adopted the lower MLDA of 18. During the late 1970s and early 1980s researchers found a significant increase in youth auto-fatality rates. They argued that increasing alcohol availability to year olds increased the chance of them getting into an alcohol-induced fatal crash. These studies combined with political lobbying groups such as Mothers Against Drunk Driving (MADD) and Students Against Drunk Driving (SADD) to put pressure on the national government to raise the MLDA. On July 17, 1984 Congress passed The National Minimum Drinking Age Act and all states were thereafter required to legislate and enforce the age of 21 years as a minimum age for purchasing or public possession of alcoholic beverages. 4 Under the Federal Aid Highway Act, states not enforcing the minimum age would be subjected to a ten percent decrease in annual federal highway funding. 5 The magnitude of this shift in MLDA was from 18 to 21, or in some cases from 19 to 21, increasing the age by about 6%. States complied quickly, and by 1988 all of the states had complied with the new law and had raised the MLDA to 21 (DiNardo 2001). 3 Dee and Evans (2001). States with 21 MLDA: Alaska, California, Indiana, Kentucky, Missouri, New Mexico, Nevada, North Dakota, Oregon, Pennsylvania, Utah, and Washington. States with an MLDA of 18: Colorado, Kansas, Louisiana, Mississippi, New York, North Carolina, Ohio, South Carolina, Tennessee, Virginia, West Virginia, and Wisconsin 4 Also known as the Uniform Drinking Age Act 5 DeJong and Hingson (1998) 5

7 Figure 1: Percent of U.S. Population Age Covered by MLDA of Percent Year Source: Hedlund, Ulmer, Preusser Canada Legislation on MLDA Canada s drinking age is determined by province. For over the past thirty years the ages have remained constant with three provinces having an MLDA of 18 (Alberta, Manitoba, and Quebec) and the other nine having a MLDA of There has not been public support for raising the MLDA in Canada primarily because it is seen as culturally undesirable. It is hard to justify to the public that year olds ought to be treated like adults in all aspects except for drinking. Wagaenaar phrases this argument best by stating, it may seem unfair to many observers to allow year olds to marry, to have children, to own cars, homes and firearms and to be financially and socially independent, and yet to be legally prohibited from drinking a glass of wine in a restaurant, or even a glass of champagne at their own wedding." -Wagaenaar Hedlund, Ulmer, and Preusser

8 Although the majority of Canadians are not interested in raising the MLDA, they are still concerned with alcohol-related traffic fatalities. The Canadian Council of Motor Transport Administrators (CCMTA) a branch of Transport Canada has put together a comprehensive plan to reduce traffic fatalities by The annual report, Road Safety Visions 2010 outlines how the administration hopes to cut the percentage of crashes that involve alcohol by 40% Other Relevant Laws and Economic Factors Although the main interest of this paper is the effect of the shift in drinking ages, it is important to point out the other laws that were being implemented during this time period. The 1970s and 80s had various legislation intended to increase road safety. In 1984 Congress passed a mandatory seat belt law which was found to reduce traffic fatalities among 16 and 17 year olds by nearly 8% and year olds by almost 10%. 8 National maximum speed limits also helped reduce traffic fatalities (Dee and Evans 2001). The following Table summarizes the estimated impacts of different policies to reduce drunk driving. 9 7 Transport Canada, Road Safety Vision See their website for details: 8 Dee and Evans Assuming primary enforcement of seat belt laws. 9 All estimated impacts are for the United States 7

9 Figure 2: Impact of Strategies to Reduce Driving Under the Influence of Alcohol Lower per se limits Zero Tolerance Laws Alcohol Control Policies Minimum Legal Drinking Age Increased Alcohol Excise Tax Strategy Impact Reference: General Deterrence Policies Administrative License 9% decline in alcoholrelated Klein (1989) Revocation fatal crashes Sobriety Checkpoints 17% decline in alcohol- Lacey, Jones, Fell (1996) related fatal crashes 16% decline in the proportion of fatal crashes involving drivers at 0.08% BAC and higher 20% decline in the proportion of singlevehicle, nighttime fatal crashes among year old driver 10-15% decline in alcoholrelated traffic deaths among driver under age 21 15% decline in traffic deaths among drivers ages Hingson, Heeren, Winter (1996) Hingson, Heeren, Winter (1994) Wagenaar (1981) Saffer and Grossman (1987) Source: DeJong and Hingson 1998 Besides drinking ages, the other main attempt at controlling alcohol usage is through alcohol excise taxes. Alcohol taxes affect everyone, so they are not as targeted as a MLDA, but youth can evade drinking age laws whereas they have to pay taxes. A study by Saffer and Grossman looked at the correlations between high taxes and traffic fatality rates for certain age groups. They found that youth alcohol consumption is negatively correlated with price and that teens substitute other leisure activities for drinking if prices are high. Moreover, they argue that accident mortality is negatively correlated with the price of alcohol. A similar study estimated that the tax elasticity of 8

10 the fatality rate is overall and for year olds. 10 The conclusion these studies draw is that a small increase in alcohol taxes could create the same reductions in fatality rates as a shift in the MLDA. In the United States, Congress has been hesitant to increase the tax on alcohol. The taxes have been stagnant since 1951 so inflation has decreased the value of beer and liquor taxes by about 20% of their original cost. 11 Alcohol taxes are regressive taxes, affecting everyone regardless of income, and are politically difficult to pass despite their proven efficiency at lowering traffic fatality rates. Another important policy that is related to a MLDA law is the Zero Tolerance (ZT) law. ZT laws are complimentary to MLDA laws because they criminalize young drivers with any alcohol in their systems; the legal limit is somewhere between a BAC of g/dl. The main economic argument for ZT laws are that they are the best policies because they are the most specifically targeted at the type of drinking that is bad for society drinking while driving. Also, zero tolerance sets an easily defined limit. Individual drinkers are often time uncertain about when they reach a BAC level of 0.08 the adult legal limit for both the U.S and Canada. There is confusion over how many drinks it takes and how much alcohol is in one drink. A zero tolerance law ends this uncertainty because people can be certain that if they drink heavily they will be over this new stricter limit. In the United States, zero tolerance laws are present for all drivers under the age of 21. This was enacted by Congress in their 1995 National Highway Systems Designation Act, legislating that any state not enacting a BAC limit of 0.02 g/dl or less 10 Cook and Moore (1994) 11 Saffer and Grossman (1987). There was one slight increase in alcohol taxes in

11 for young drivers would lose 5% of its federal highway funds for that year and 10% each subsequent year. 12 Once a driver turns 21, however, they are then subject to the adult BAC limit of 0.08 g/dl. In Canada, seven of the twelve provinces have a ZT law in place, with one province (Manitoba) in the process of making a new ZT law (NHTSA 2000). An econometric study done on U.S data was conducted by Christopher Carpenter who studied the effects of ZT laws on self-reported alcohol use and driving drunk using data from the Behavioral Risk Factor Surveillance System (BRFSS) 1984 to Carpenter concluded that the (ZT) laws reduced heavy episodic drinking (5 or more drinks at one sitting) among underage males by 13%. Furthermore, the implementation of ZT laws increased the likelihood of being a light drinker as well as decreased the overall number of drinks consumed by young males. There weren t any significant effects on the drinking behaviors of young women that he could find. His results argue that ZT laws can change drinking behavior of some young adults and thus can reduce the quantity of drunken drivers. 13 The combinations of all of these laws make it difficult to distinguish the sole effects of MLDA on traffic fatalities. Moreover, other potential factors exist that effect alcohol use and drunk driving that have yet to be accounted for. Any factor that affects alcohol use may consequently affect alcohol-related traffic fatalities. For example, according to one study, state unemployment rates are negatively correlated with alcohol use (DiNardo and Lemieux 2001). Unemployment and other economic conditions may interact with trends in rates of fatal car crashes. 12 Dejong and Hingson All the states complied with this law by July of Carpenter This study was conducted under the University Of Michigan School Of Public Health. 10

12 III. Literature Review on the Effects of Raising the MLDA 3.1 The Age Effect. Raising MLDA and Reducing Alcohol-Related Auto Fatalities The intent behind a MLDA is to decrease the supply of alcohol to teenagers in order to prevent a range of negative consequences that arise with alcohol abuse. According to a study by a collaboration of doctors at the Boston University of Public Health, adults who start drinking at the age of 14 were three times more likely to self report driving drunk and four times more likely to be in an alcohol related car crash than their peers who started drinking at the age of 21 (Hingson 2002). Delaying access to alcohol has clear personal health and societal benefits. Unfortunately, a MLDA is not completely enforceable, as some teenagers acquire alcohol from older friends, strangers, or from using fake IDs. Although some evasion occurs, there is still evidence that raising the MLDA decreases alcohol use and heavy teen drinking. According to a study by Thomas Dee, raising the MLDA from 18 to 21 reduced heavy teen drinking by MTF respondents by 8.4%. 14 As a MLDA makes alcohol less accessible, studies have found that teens substitute marijuana for alcohol. One study estimated that changing the MLDA from 18 to 21 decreases alcohol prevalence by 4.5 percentage points but also increases marijuana prevalence by 2.4 percentage points (DiNardo and Lemieux 2001). If teens are consuming less alcohol when faced with a higher MLDA, it is logical to assume they will get in less alcohol-induced traffic accidents. Various studies have proven this effect. Data taken from the national high school survey, Monitoring the Future, shows that raising the MLDA to 21 reduces traffic fatalities by at least 9% (Dee 1999). Likewise, a study on the effects of raising Michigan s MLDA from 18 to Dee MTF respondents are high school seniors who took the Monitoring the Future survey. 11

13 estimated that single-vehicle nighttime crashes for year olds were 16% lower then the expected level (Waganaar 1986). As a final point, the NHTSA estimates that the movement to a higher MLDA has saved over 23,000 lives since 1984 (NCSA 2004). The results from these studies were the driving force behind the movement to raise the national MLDA in the 1980s. 3.2 The Experience Effect: Raising MLDA and shifting fatalities to older ages. One critique of the previous studies correlation between higher MLDA and lower teen traffic fatalities is that the studies do not account for the bigger picture of overall traffic fatalities. Teens have high rates of accidents because they are inexperienced driving and inexperienced drinking. Understandably this creates two added risks to teen driving and they consequently have a higher accident rate then adults. If becoming a new drinker creates an extra risk for getting into car crashes, we would expect to see a shift in fatalities when the MLDA is attained no matter what this age is. 15 This implies that the national increase of MLDA from 18 to 21 may have shifted some of the fatality risks from teens (16-20 year olds) to young adults (21-25 year olds). Some research has been done that supports this theory. A 2001 study found that, among 23 and 22 year olds, those who faced an MLDA of 19 at age 18 had, respectively, 8.9 and 7.5 percent fewer passenger-vehicle fatalities than those who could legally drink at 21 (Dee and Evans 2001). Asch and Levy call this effect the Experience Effect because it recognizes the learning-by-doing aspect of alcohol consumption. This theory argues that increasing the 15 Asch and Levy

14 MLDA from 18 to 21 may reduce year olds fatalities but will also increase fatalities for people 21 and over. Arguably a net life-saving effect can occur if the reductions are greater then the increases. If this experience effect is significant, then the gains to increasing the MLDA may be overstated in studies that correlate drinking ages to traffic fatality rates. For example, a 1986 study by the National Institute of Alcohol Abuse and Alcoholism calculated a 19.5% reduction in alcohol related crashes from an increased drinking age by adding up a 6% decrease on year old crashes and a further 13% estimated decrease. 16 This estimated decrease was found by comparing the difference between year olds crash involvement in states where the MLDA was 21 to the crash involvement of people in that same state who were 21 and over. The report states that: Drinking drivers 21 and over experienced a significant 13.4% increase in their rate of involvement in injury producing crashes in the early 1980s. Thus, the raised drinking age apparently prevented year olds from experiencing the same 13.4% increase in the rate of HBD (had-been-drinking) crash involvement that occurred among those 21 and over. -Wagaenaar 1986 Clearly, adding up the 6% decrease from year olds accident rate and the 13% increase in 21 and over accident rate does not capture the true effect of the MLDA law if the law caused some of those increases in the 21 and over accident rates. Comparing age-specific fatality rates between the U.S. and Canada can help determine how natural the increase in the fatality rates for young adults was after the implementation of the higher MLDA. If Canada s 21 and over age cohort did not see similar increases in traffic fatality rates in the 1980s, then it is possible that the MLDA life saving effect was less then previously estimated in the United States. 16 Wagenaar

15 The policy implications from the Experience Effect are seen by focusing efforts not on MLDA laws but on graduated license programs. Graduated licenses capture the benefits of learning-by-doing by restricting access to risky driving situations. Young drivers are granted the privilege to drive in a series of stages. Often under these programs licenses are granted with restrictions for the first 6 months to 2 years to help new drivers become experienced driving in safe environments before they drive in more risky environments. For example, California s current law allows newly licensed 16 year olds to drive only during the hours of 6am to midnight for the first six months of their license. 17 Many studies have shown that alcohol involvement in fatal accidents is higher during the nighttime, so restricting access to both the alcohol (MLDA) and the driving at night (graduated licensing) would be the best approach to decreasing nighttime crashes. 18 IV. Approach/ Strategy To interpret the effect of raising the MLDA in the United States I am comparing the relationship between an input (minimum age legislation) and the output (auto fatalities). This approach does not specify or prove the causal mechanism which links them; however many studies have hypothesized different theories for how MLDA s affect auto fatalities. As explained above, previous studies have found mixed results on the magnitude and effects of a shift in the MLDA. I interpret how this new data fits into previous theories on the relationship between MLDA and auto fatalities. Specifically, I want to see if comparing the U.S. data to Canada supports the standard assumption that States including California have a graduated license system in place. Likewise, 10 of 12 provinces in Canada have them as well. 18 Dee A NHTSA repot in 1998 found that during alcohol was involved in traffic fatalities 68-75% of year old driver crashes between midnight and 5am whereas its only 10-20% from 7am to 3pm. 14

16 MLDA lowered fatality rates (the age effect) or if it shifted some of these deaths to young adulthood (the experience effect). The advantage of comparing the United States and Canada lies in their similarities. Figure 3 compares different variables in the U.S. and Canada. 19 Figure 3: Comparing the United States and Canada 2004 United States Canada Road Safety Factors BAC limit 0.08 g/dl 0.08 g/dl Passenger Vehicles per 1000 People (1998 levels) Paved Roads, as Percent of Total Roads (1995) Economic Factors GDP per capita (constant 2000 US $) $36, $24, Public Spending on Education (% of GDP) (2000) Hospital Beds per 1,000 People (1999) Unemployment Rate (% of total Labor 6 7 Force) Cultural/ Demographic Factors Per Capita Consumption of Absolute Alcohol in Liters 20 Crude Birth Rate per 1,000 People Crude Death Rate per 1,000 People Population aged (as percent of total) The fact that the U.S. and Canada are similar on some variables does not indicate that they are similar in most comparisons. It simply points out that Canada is a good candidate to compare to the U.S. when using natural experiments where we cannot alter the treatment and control groups to be random. 19 Data taken from the World Development Indicators, part of the United Nations Common Database and the World Bank Group, from 2004 unless otherwise noted. 20 NHTSA 2000, estimating 1995 levels 15

17 We treat the absence of a higher MLDA in Canada as a natural experiment on the effects of MLDA on auto fatality rates and view the results in comparison to the U.S. This allows another dimension of policy analysis as we can see which theory holds up when you expand beyond U.S. data. Canada is a good comparison because they are in proximity to the U.S. and have similar roads, economies and cultures. Furthermore, Canada s MLDA has been steady throughout the changes in U.S. law. V. Data Section 5.1 Sources of Data Data for the United States is taken from the National Highway Traffic Safety Administration (NHSTA). NHSTA maintains a census of all motor vehicle traffic accidents that involve a fatality. The Fatal Accident Reporting System (FARS) includes detailed information on the characteristics of the involved vehicles, drivers, occupants and non-occupants. Data for Canada is taken primarily from the Traffic Injury Research Foundation (TIRF), which maintains a database of results from tests for alcohol in the fatally injured drivers in seven provinces (British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, New Brunswick, and Prince Edward Island) from After 1987 the Fatality Database was expanded to include all ten provinces and the two territories. Supplementary Canadian data is taken from Transport Canada and their affiliated publications. The TIRF data differs from the FARS data in a few important ways. First, the Canadian data records driver fatalities instead of driver involvement in fatal crashes. This 16

18 limits comparisons slightly, as we can only compare driver fatalities over both countries instead of overall driver involvement per age group. The next major difference between the countries is in how they categorize and organize the crash data. In the United States we categorize age groups into those who are less then 16, 16-20, 21-24, and so on. Canada, however, groups the ages into those less then 15, 15-19, 20-24, and so on. The age groups in each country are similar after age 25. The young adult data in Canada is aggregated into groups that are a year off from the U.S. data. At first I ignore the difference in data categories in hopes they do not affect overall comparisons. I then try to adjust for the year difference by re-arranging the age groups to match up. The last major difference in the Canadian data is that the TIRF does not estimate alcohol presence for a driver without a BAC test. Fortunately, most drivers are tested: 76% of the age driver fatalities in 1982 and 93% in These differences should not affect the data when looking at overall trends of traffic fatalities, yet it should be noted that the comparisons are not exact. There has been some attempt at international comparison of this sort of data. The OECD s International Road Traffic Accident Database (IRTAD) and studies complied by the UN offer a good resource for contrasting data across different countries, and some of their papers are quoted in this study. 5.2 Disadvantages with the Approach There are a few disadvantages to comparing cross-country statistics. For example, the treatment and control groups (U.S and Canada) might differ in important ways, either before or during the study period which could bias the results. Some of these differences 21 Hedlund, Ulmer, Preusser

19 can be accounted for, such as population levels, whereas others are less concrete and hard to measure. Another potential omitted variable is the effect of some similar exogenous law that aims to decrease total automobile fatalities. These laws are examined in the historical background section of this paper yet it is important to point out that it is difficult to distinguish and calculate the effects of each law separately. The last major disadvantage with this comparison is that I am focusing on broad indicators, such as total fatality rate per 100,000 people, and not specific behavioral changes, like using a designated driver. The reason for choosing fatality rates as a dependent variable is that it is well documented in both countries. Specific behavioral changes are harder to measure even though they most likely have significant impacts on decisions to drive drunk. In previous studies on the affects of MLDA, additional control variables are often accounted for. Examples of these variables are the natural log of the population for each age group; the unemployment rate; real personal income per capita; and year fixed effects. I do not include these additional controls, although I do comment on their potential impact on the results. VI. Empirical 6.1 Overall Trends In the United States, and most other developed countries, there has been a notable decrease in traffic fatality rates since the 1970s. According to the National Highway Traffic Safety Administration, (NHTSA), the occupant fatality rate per 100,000 people 18

20 declined by 24.6% from 1975 to Internationally, a World Bank Study found that the mean road death rate of the OECD countries has fallen by half since 1970, from 34 deaths/ 100,000 persons in 1970 to approximately 12 deaths/100,000 persons in 2000 (Kopits and Cropper 2005). There have been declines in the fatality rates per 100 million vehicle miles traveled since the 1970s, when much of the legislation aimed at preventing drunk driving became enacted. These trends are similar in Canada. Traffic fatalities in 2001 are half of what they were in Alcohol-related traffic fatality rates have decreased as well a one-third decrease since Despite gains to traffic safety, driving while intoxicated continues to be a major problem for Canada; compared to Canada s national homicide rate, drunk driving kills two times the number of Canadians murdered each year. 24 The following graphs show the traffic fatality rates in the U.S. and Canada since Figure 4: Traffic fatalities since 1970 per 100,000 populations Source: IRTAD 30/ NHTSA, Traffic Safety Facts Mayhew, Brown and Simpson SADD Canada website, referencing Statistics Canada 19

21 From the graphs it appears that overall trends of decreased traffic fatalities are rather similar for both countries. During the 1990s, however, the U.S. fatality rates stabilize while Canada s continue to fall. The following graph shows road fatalities per million people in each country in the past decade. Figure 5: Road Fatalities per Million Population in the United States and Canada Fatalities per Million Population United States Canada Year Source: OECD Factbook 2005 It is unclear why the 1990s yield so little change in the U.S. fatality rates. Canada s levels also stabilize somewhat, compared to the sharp decreases of the 1980s. One can speculate that the reason for the stabilization of fatality rates may be due to the lack of public attention traffic safety issues have received in the 1990s. Drunk driving initiatives were a higher political priority in the 1980s and the attention it received may be the driving force behind some of the decreases from that time period. 20

22 Other factors to consider when viewing the overall trend include: improved technology in car safety features such as anti-lock breaks and air bags, social improvements in health care and health services, and social norms changing considering wearing a seat belt and driving under the influence. 25 Also, with continuing social pressure to crack down on intoxicated drivers, police arrests and DUI tickets have increased since the 1970s, which would also decrease the overall amount of crashes. However, this effect has not curbed the problem of drunk driving when in 2002, one out of every 130 licensed drivers or 1.5 million drivers in the U.S were arrested for driving while intoxicated (NCSA 2003). When comparing crash statistics internationally one has to account for the differences in population. Canada is a smaller country then the U.S. and will naturally have fewer crashes. That s why we take the fatality per 100,000 or million population instead of the absolute number of crashes when comparing the U.S. and Canada. The Canadian trends tend to fluctuate more then the U.S. trends since the absolute number of crashes is less in Canada. Overall, however, the two countries both show decreasing crash rates throughout the 1980s. 6.2 Alcohol-Related Crashes The overall trends in alcohol-related crashes also appear to be rather similar for the U.S. and Canada. Both countries had around 60% alcohol involvement of their fatal crashes in By 2003, however, alcohol is a factor in only 40% of U.S. fatal crashes and around 37% of Canadian crashes. 25 Tessmer Studies show seat belts increase the probability of crash survival by 50-60%. Other factors that improve car safety include the use of daytime running lamps, improved roads, etc. 21

23 Figure 6: Alcohol Involvement in Fatal Car Crashes Percent Alcohol-Related Traffic Fatalities United States Canada Year Source: NHSTA and Transport Canada 2004 The U.S. and Canadian curves do not diverge from each other in the expected direction once the 1984 legislation is passed. Even by 1988, when all U.S. states had adopted the higher MLDA of 21, the U.S. did not gain extra reductions in alcohol-related traffic fatalities compared to the subsequent decreases that were going on in Canada at the time. In fact, around 1988 the graph indicates that Canada actually had greater reductions in fatalities. This indicates that overall, the MLDA change was not the most significant factor at achieving substantial reductions in alcohol-involved traffic fatalities. The next graph adds in linear regression estimations of each countries traffic fatalities over time. The linear regressions point out that in the period from , Canada has been slightly more effective then the U.S. at reducing the percentage of alcohol-related traffic fatalities. 22

24 Figure 7: Alcohol Involvement in Fatal Car Crashes Percent Alcohol-Related Traffic Fatalities Year United States Canada Linear (Canada) Linear (United States) Source: NHSTA and Transport Canada 2004 Even if Canada has had a higher percentage drop in fatalities, the overall trends for both countries are similar. There does not appear to be a clear divergence once the 1984 change in MLDA occurred. 6.3 Teen Crashes As the main focus of MLDA targets teenagers, we should look at teenage driving to single out the effect of the law. Teen crashes in the U.S. have fallen substantially in the past few decades. During teen traffic fatality rates fell by 37%, with the bulk of this drop (25%) occurring from (Dee and Evans 2001). In 1982 drivers under the age of 21 had 4,393 fatal crashes while in 1999, they were only involved in 1,687 (Hedlund, McCartt 2002). These reductions are particularly impressive considering the increased amount of vehicle miles traveled (VMT) by teens since the 23

25 1980s. VMT by teens aged doubled from Taking this into account, teen fatality rates have fallen by 50% since 1983 if denominated by VMT (Dee and Evans 2001). Alcohol-related car crashes have also decreased for teens. The NHTSA estimates that alcohol-related teen fatality rates decreased by 61% from (Hedlund, Ulmer, Preusser 2001). The following graph shows the trends of alcohol involvement in car crashes for people aged 16-20, and years old over the time Figure 8 Percent of American Driver Fatalities by Age Group with Positive BAC Drivers Drivers Drivers Percent Year Source: Traffic Safety Facts 2004, NHSTA Figure 8 shows that teen drivers have had the most reductions in alcohol-related fatal car crashes. During the late 1990s, however, all three age groups see little change. The period of sharpest decline occurred during Some of this decline is due to there being fewer teens in general. The population of teens aged in the U.S. 24

26 dropped 6% during while the population of adults aged rose 31% (Hedlund and McCartt 2002). The trends are similar in Canada. Teens have decreased both their overall number of traffic fatalities and their percentage of alcohol-related crashes. Figure 9: Percent of Canadian Driver Fatalities, Age 16-19, with Positive BAC Source: Hedlund, Ulmer, Preusser 2001 The trends are similar for Canada even though their absolute percentages are higher then the U.S. For example, the 1982 Canadian level is 67% whereas the 1982 U.S. level is 43%. One way to compare the trends in each country is to set 1982 as the base year and then graph the percent change from that level in subsequent years. In this format, the decreases in alcohol-related fatal crashes appear similar in the U.S and Canada. 25

27 Figure 10: US and Canadian Trends, Percentage Change from 1982 US: Drivers Under Age 21 in Fatal Crashes with Positive BAC (FARS) Canada: Driver Fatalities Age with Positive BAC (TIRF) Source: Hedlund, Ulmer, Preusser 2001 Another way to break down the data is to look at specific years and see the age distribution on the drivers involved in fatal crashes. The most recent data is for 2004 which is used to make the graph below. Figure 11: Drivers of Fatal Car Crashes by Age Group Percent of All Drivers in Fatal Crashes United States Canada Unknown Driving Age (Years) Sources: NCSA Traffic Safety Facts 2004 and Canadian Motor Vehicle Collision Statistics

28 The results are that the U.S. has more year old drivers involved in fatal crashes and less year old drivers then Canada. I had expected it to be the opposite because both the age and experience effects. One important note about this data is that the comparisons are slightly off age cohorts in the U.S. are compared with year olds in Canada. Also in the U.S. is compared with in Canada. To check if the year difference is significant I re-arranged the data to line up the age groups. I estimated the rates per individual age year as a fraction of the original age group it was in. Figure 11.2 shows the results of rearranging the data to deal with the year difference in age groupings. Figure 11.2 Drivers of Fatal Car Crashes by Age Group (Adjusted Data) Percent of All Drivers in Fatal Crashes United States Canada Unknown Driving Age (Years) Sources: NCSA Traffic Safety Facts 2004 and Canadian Motor Vehicle Collision Statistics 2004 In Figure 11, U.S year olds had a much higher involvement in fatal crashes then their year old Canadian peers and U.S year olds had less crashes then 27

29 the year old Canadians. When adjusting the data, the magnitudes of the differences between the U.S. and Canadian young adult levels are reduced, as seen in Figure 11.2 These results are surprising because as U.S. teens face a higher MLDA, we would expect them to have less crashes then Canadian teens. The year old group includes legal drinkers in Canada yet they still have less crashes then American teens that are all legally underage. The next graph shows fatal crashes by age group and by alcohol involvement. Again, there is the complication with the ages not being directly comparable. Drivers less then 16 years old were omitted because they constituted a negligible amount of alcohol-related fatalities. 26 Figure 12 Percent of All Fatally Injured Drinking Drivers by Age Group United States Canada Percent >55 Driver Age (Years) Source: NCSA Traffic Safety Facts 2004 and The Alcohol- Crash Problem in Canada NHSTA estimated drivers less then 16 were responsible for around 0.3% of all alcohol-related fatal crashes. 28

30 The results for alcohol-related crashes are similar to the results for all fatal crashes. In 2004, U.S. teenagers ages had a higher percentage of alcohol-related fatalities then Canadian teenagers. The opposite is true for American year olds. However, when adjusting the data using the same method as before, the results change. Figure 12.2 Percent of all Fatally Injured Drinking Drivers by Age Group 2004 (Adjusted Data) Percent 15 United States Canada >55 Driver Age (Years) Source: NCSA Traffic Safety Facts 2004 and The Alcohol-Crash Problem in Canada 2003 Using the adjusted data, American year olds are involved in a higher percent of all alcohol-related fatal crashes then their year old Canadian peers. This result supports previous theories on the Experience Effect as we see an age group that is new to alcohol participating in more alcohol-related crashes. Another difference in the adjusted data is that year olds constitute a higher percentage of alcohol-related fatal crashes in Canada then in the U.S. This result supports the Age Effect theory of the 29

31 MLDA, as year olds in the U.S. have less access to alcohol then Canadian year olds, so they consequently get in less alcohol-related fatal car crashes. These findings may not hold a lot of statistical ground because it is unlikely that my estimates are accurate. I m assuming that 20, 21, 22, 23, 24, and 25 year olds all constituted an equal amount of traffic fatalities, and then switching the 20 year olds portion of fatalities (1/5 of the age cohort 20-25) to the younger age cohort (16-20). Similarly, I assume all 16, 17, 18, and 19 year olds each account for ¼ the crashes in their age group of If we had the age specific data for each year, we would assume the rates to differ between each year of age. The following table shows data from Canada that 19 year olds have a much higher percentage of involvement with fatal crashes then 16 year olds (50% compared to 33%) in Figure 13: Percent of Drinking and Legal Impairment by Age in Canada Fatally Injured Drivers Age Had-Been- Legally Impaired Drinking % 30.8% % 25.8% % 22.2% 19 50% 40.3% Source: Mayhew and Simpson 1999 Although the 2004 data can present one story, the overall trends of Canadian and U.S. teen fatality rates are extremely similar. The 2004 data could be an example of a fluctuation and not represent the overall trend. To test this, I look back to the trends of teen crashes and young adult crashes in Canada and the U.S. 30

32 Figure 14: Percent of Drivers in Fatal Car Crashes that are Legally Intoxicated (BAC>0.08) by Age Group Percent U.S CAN <19 U.S CAN Year Source: Traffic Safety Facts 2004 and Road Safety in Canada 2001 According to Figure 14, U.S. teens have been less likely then Canadian teens to be legally intoxicated when involved in a fatal car crash. Likewise, U.S. young adults have a lower rate of intoxicated drivers in fatal crashes then Canadian young adults. Notice, however, that the age groupings are different for each country. American young adults are grouped as ages whereas Canadian young adults contain everyone in the ages I next adjust the data so that we can compare U.S. and Canadian young adults within the exact same age grouping. 31

33 Figure 15 Drivers in Fatal Car Crashes who are Legally Intoxicated (adjusted data) U.S CAN Percent Year Source: Traffic Safety Facts 2004, Road Safety in Canada 2001 Figure 15 shows that between year olds, Americans actually have a higher percentage of drivers in fatal car crashes that are legally intoxicated. This result is consistent with the adjusted data results from earlier. These trends support the theories on the age effect and the experience effect. VII. Conclusion There have been substantial decreases in youth drinking and driving since the early 1980s. There is not a specific reason why alcohol-related fatality rates have decreased, but we can infer that a combination of policies helped create this drop. Changing the MLDA might have decreased teenage drinking and driving and may have also helped promote a cultural taboo against driving drunk. The change in the 32

34 MLDA did not, however, cause the majority of the decreased auto-fatality rates due to the fact that similar decreases occurred in Canada without a change in drinking age. The age specific data showed that both countries experienced substantial decreased fatality rates over the past few decades namely in the 1980s. Other factors are working to decrease the fatality rates that may or may not be measurable. Examples of other factors that occur in the U.S. and Canada are active citizen groups such as MADD and SADD, various drunk driving legislation such as ZT laws or punishments for DUIs, and vigorous public education campaigns. Future studies could incorporate these factors into models estimating the impact of the U.S. s higher MLDA. The result from comparing age specific data in the U.S. to Canada does support previous research on the effects of the MLDA. When adjusting the data to create comparable age groups, I found that Canadian teens (16-20) are involved in more alcohol-related fatal crashes then American teens. This is presumably a result of Canadians teens legal access to alcohol. Moreover, Canadian young adults (21-25) appear to constitute a slightly less overall percent of alcohol-related fatal crashes then American young adults. This result arguably is a result of American young adult s lack of experience with alcohol because of the higher MLDA, creating an added risk of alcoholrelated car crashes when first exposed to alcohol. The statistical methods used to obtain these results, however, are not precise. The issue of measurement error weakens my results. Besides the potential measurement error, the problem with my analysis is that it covers too broad a topic. A change in MLDA may affect traffic fatality rates to some degree, yet this effect is hard to distinguish in the aggregate data. 33

35 MLDAs ought not to be discounted as ineffective. Other studies have shown that a MLDA has positive externalities on society such as increasing the probability of graduating college by 4.2%. 27 A MLDA also sends out a strong social message about cultural expectations not to drive drunk. There is plenty of room for future research to expand upon the relationship between MLDA and traffic fatalities. After taking the overall trends into account, studies can look at other variables as well and try and see which has had the biggest impact on fatality rates. Examples of such variables have been mentioned earlier in this paper and include other U.S. legislation; general economic variables to capture the state of the economy in both the U.S. and Canada in the 80s; drunk driving education programs; and youth behavior changes. Another aspect to include in future research is to include the effects of alcohol taxes. Taxes are another form of an alcohol control policy and have been found to be effective at reducing the demand for alcohol and consequently reducing drunk driving. Looking at Canadian and U.S. alcohol tax rates may explain why Canada was able to decrease their fatality rates without a change in MLDA. This study could be enhanced with access to more data. It would be interesting to look at trends of crash participation for every age, instead of age groupings. Ideally, the data would be gathered by a common source, so that the technique is the same for both Canada and the U.S., eliminating potential differences in data collection and recording methods. 27 Cook and Moore (1994). Calculated effects of changing the MLDA from using data between states. 34