The federal government, however, would withhold some highway transportation funding to states which allowed drinking at a lower age. The U.S. population have for decades been heavy users of personal automobiles for transportation, and hence car accidents are relatively common, taking around 43,000 lives a year. According to proponents such as Mothers Against Drunk Driving , the relatively high US drinking age lowers the risk of accidents and alcohol addiction in younger people. Some studies support this claim, though others suggest that accidents and the learning curve for handling alcohol are simply moved to the 21+ demographic, perhaps not even saving any lives. Some people argue that if one is old enough to vote and be drafted (or voluntarily join the military), one is old enough to drink, and that being introduced to alcohol at a younger age in a family environment means people are more likely to learn responsible drinking habits. Many also consider it reasonable for college students to experiment with alcohol before they are 21, as long as it is done safely.

While the legal drinking age is 21 in all states, the legal details vary. Some states do not allow those under the legal drinking age to be present in liquor stores or in bars (usually, the difference between a bar and a restaurant is whether food is being served). Contrary to popular belief, few states specifically prohibit minors' consumption of alcohol in private settings.