The age of 21 is one of, if not the highest drinking age in the world. It actually used to be 18 up until 1984, but then they decided that they can trust an 18 year old with voting for the future of our country, but can't trust that same 18 year old with a can of beer.
I actually hate the whole 21 years old thing not because it denies me alcohol - I can get it relatively easily despite the law. I hate the nationwide 21 years old drinking age because of the way it came about.
When Prohibition proved a colossal failure in the 1930s and they repealed the total ban on alcohol, they had to make an amendment to the United States Constitution. Summed up, it legalized booze, but left it up to the individual states to regulate it. That meant that each state could set their own drinking age. While the federal government would probably have preferred to set some more rules when the re-legalized alcohol, they had no Constitutional power to. There's an amendment to our Constitution - the 10th amendment - that says, in short, that the federal government has the powers and only the powers expressly granted to it by the Constitution. Anything else falls to the states. It says nothing about alcohol or the regulation of in the Constitution outside of the amendment banning alcohol and the subsequent amendment repealing the ban. So when they un-banned alcohol, I imagine they would have liked to set some limits on it, but they actually had no legal power to. The states had to come up with their own.
So most states ended up setting their own drinking laws, and most of them set the legal drinking age at 21. This was the voting age of the time, the point when a person would be considered a complete adult with all rights and privileges associated. When they lowered the voting age from 21 to 18 with the onset of the Vietnam war and the draft pulling a lot of 18 year olds into military service, most of the states followed suit by lowering their drinking ages to 18, 19, and 20, as was their right.
Well, in 1984, a group called MADD (Mothers Against Drunk Driving) comes along and manages to convince the federal government that not only do we need a uniform drinking age across all the states - we need it to be set at 21. To any politician, I imagine it would be something hard to argue against. Less teens dunk on the road? Stricter control on drunk driving? This means that anyone who doesn't support this initiative must be in favor of dead kids, right? Well, that's the logic they used to pass the National Minimum Drinking Age Act of 1984.
But remember how I said above that the federal government doesn't have any power given to them by the Constitution to actually force all states to have a uniform drinking age? Well, technically, they don't. What they did was hold the federal money hostage. Until such time as a state would set their minimum drinking age to be 21, the federal government would withhold up to 10% of the money the government gave to the states for use in highways. This was a very large chunk of change. As you can imagine, most states ended up complying.
So the reason I hate the drinking age of 21 isn't because it denies me access to alcohol. I can still get that anyways. I hate it because in the 80s a special interest group stomped all over both the constitutional powers of the states from the 10th amendment AND the individual rights of legal adult citizens. If I am apparently to be trusted voting for the future of my country - which I did for the first time this past November - AND am considered mature enough to join the army and go to war, risking my life by my choice, why am I not to be trusted with alcohol?