Before the twentieth century, few laws controlled the consumption of alcoholic beverages by youth. Laws prohibiting the sale of alcohol to minors were first put in place early in the twentieth century, as part of a broader trend of increasing legal controls on adolescent behavior. During the period known as Prohibition, from 1919 to 1933, the sale of alcohol to people of all ages was illegal. When Prohibition was repealed, all fifty states established legal minimum ages for the buying or drinking of alcohol, with most states setting the age at 21.

From the 1930s through the 1960s, the drinking age was not an issue of great public interest. However, in the 1970s a change in the voting age led to changes in the drinking age as well. In 1970 the 26th Amendment to the U.S. Constitution lowered the voting age in federal elections from 21 to 18. By 1974, all fifty...