Minimum legal drinking age (MLDA) laws were established in the United States after the repeal of Prohibition in 1933. Many states set the MLDA at 21 during that time. When the voting age was lowered from 21 to 18 in 1971, many states lowered their drinking age to 18 or 19. Studies in the 1970s and 1980s showed significant increases in alcohol-related crashes involving youth aged 18 to 20 in states that lowered their drinking age.
Several studies in the early 1980s also found reductions in traffic crashes and alcohol-related or total crash deaths when drinking ages were raised. Consequently, the U.S. Congress adopted the National Uniform Drinking Age 21 Act, which provided a substantial financial incentive for states to adopt an MLDA of 21, and President Reagan signed the bill into law in 1984.
Since 1988, the MLDA has applied to age 21 for both the purchase and possession of alcohol in all 50 states and the District of Columbia. Between 1982 and 1998, the population-adjusted rate involving drinking drivers aged 20 and younger in fatal crashes in the United States decreased 59 percent.
MLDA-21 laws have been shown to be independently associated with part of this decline. The National Highway Traffic Safety Administration (NHTSA) has estimated that MLDA laws save approximately 900 lives a year in traffic fatalities alone. Other studies show reductions in homicides, suicides, and unintentional injuries by 18- to 20-year-olds associated with raising the MLDA to 21.
Despite the laws raising the drinking age to 21, underage drinking is prevalent in America. Even facing strong evidence of the effectiveness of MLDA-21, there are movements in some states and by some organizations to lower the drinking age again. There is no evidence that lowering the MLDA will reduce the underage drinking problem. Conversely, there is strong evidence that lowering the drinking age will increase youthful alcohol consumption and alcohol-related injuries and fatalities.