Eighteen is the age of majority in the United States. At eighteen years of age, it is legal to vote, purchase tobacco, and risk death in war, but the minimum age to consume alcohol is 21 years.
The rationale used to justify setting the national standard for alcohol consumption to age 21 in 1984 was almost exclusively based off of fear of intoxicated drivers. Not only is it questionable if the 21 rule has truly made significant positive impact on the number of DUI-related deaths, but it has arguably backfired. Underage people continue to drink underground, which cripples opportunities for safer and more controlled consumption.
While the human brain is still developing at age eighteen, alcohol is still dangerous for all ages. Does barring adults from alcohol under 21 really make sense?