<P> Alcohol consumption by youth in the United States of America is an umbrella term for alcohol consumption by individuals under the age of 21 in the country . </P> <P> Although the minimum legal age to purchase alcohol is 21 in all states (see National Minimum Drinking Age Act), the legal details vary greatly . While a few states completely ban alcohol usage for people under 21, the majority have exceptions that permit consumption . </P> <P> Underage drinking has become an activity primarily done behind closed doors . Typically, underage drinkers hide their alcohol consumption by drinking quickly before they go out, which is often referred to as pregaming or pre-partying . Brittany Levine explained in her article "Pre-Gaming" in USA Today that "of all drinking events involving pre-partying, 80% involved additional drinking afterward ." Those who oppose a complete ban on underage drinking argue that it is important that minors be introduced to alcohol in a controlled environment, so that supervision and guidance might occur instead of experimentation . Some parents are willing to provide alcohol for their children if they drink it in a controlled environment . Furnishing alcohol to one's own children is permitted in 31 states, while it's illegal to do so for other people's children in all fifty states . Social host ordinances have been enacted in a number of jurisdictions to attempt to limit the parties where adults may permit minors to drink . Social host laws or ordinances have proliferated in the last ten years because it has been too difficult for law enforcement to prove which adults furnished or served alcohol to minors in their own home, so it permits them to cite or arrest the adult who has control of the premises . </P>

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