Raising the drinking age to 21 hasn't reduced drinking it gave under age people the urge to drink a lot more then they can consume. When people are viewed as an adult in America by the age of 18 years old, and they can limited to what they can consume, it makes people want to act out.
Proving negative reasoning as to why raising the drinking in America did not help as expected. It rather prompted people to act out and drink a lot because alcohol is not to their disposal.