For nearly 40 years, the majority of the states voluntarily set their minimum drinking age law at 21. But at the height of the Vietnam War in the early 1970s, 29 states began lowering their drinking age to more closely align with the newly reduced military enlistment and voting age. And of those 29 states, no uniformity in age limits, drinking ages varied from 18 to 20 and sometimes even varied based on the type of alcohol being consumed (e.g. 18 for beer, 20 for liquor). 

The decrease in the drinking age brought about an increase in alcohol traffic fatalities and injuries. So much so that, by 1983, 16 states voluntarily raised their drinking age back to 21, a move that brought an immediate decrease in drinking and driving traffic fatalities incidents.

Some states, however, kept a lower drinking age. This created a patchwork of states with varied drinking ages that led to what was known as blood borders, because teens would drive across state lines, drink and then drive back home across state lines killing and injuring themselves and others.

It was around this time that the nation began taking a firm stance on the issue of drunk driving. Since it was apparent that a 21 drinking age law reduced alcohol related fatalities and injuries, there was a groundswell to help decrease drunk driving deaths and injuries by raising the minimum drinking age to 21. President Ronald Reagan responded to the growing evidence that a 21 drinking age law would save lives.    

On July 17, 1984, President Reagan signed into law the Uniform Drinking Age Act mandating all states to adopt 21 as the legal drinking age within five years. By 1988, all states had set 21 as the minimum drinking age, which is where it should remain.

Since that time, the 21 minimum drinking age law has saved about 900 lives per year as estimated by the National Traffic Highway Administration (NHTSA).  In short, there are more than 25,000 people alive today since all states adopted the law in 1988. That's about as many people in a sold-out crowd at a professional basketball game or a medium-sized U.S. college.