In the U.S., turning 18 means becoming a legal adult with new and different rights, responsibilities and privileges from those of minors. If you are 18, you can register to vote, sign contracts and join the military without parental consent, along with many other changes. Some laws about what you can and cannot do at 18 vary state by state, while others are consistent throughout all, or nearly all, states.
The age for becoming an adult--and legally being able to do many things--has fluctuated over the years. In the past, turning 21 was considered the legal time for gaining the rights of an adult. Over the last 4 decades, federal and state laws have changed the age for certain rights--and then, in recent years, changed back again. The legal age for voting, signing contracts, marrying, buying tobacco products and alcohol, registering for the draft and other issues has varied over the years.
Although the legal age to vote was once 21, in 1970 it was lowered to 18. It was argued that if a person could be drafted at 18, he should have the right to vote on elected officials. Today, if you are a citizen of the United States, you have the right to register to vote and cast a ballot in all federal, state and local elections when you turn 18.
Once you turn 18, you can legally marry in nearly all states without the consent of your parents. As of 2009, you still must obtain parental consent in Nebraska if you are under the age of 19, and if you are under the age of 21 in Mississippi. In certain states, you may be able to legally marry at a younger age, but only with parental consent.
If you are male, not only are you allowed to join the armed forces at 18 without parental consent, you are required to register for Selective Service. Established in 1917, ended in 1975, then reinstated in 1980, Selective Service registration ensures the ability to draft men between the ages of 18 and 25. Any male citizen of the U.S. must register with Selective Service within 30 days of his 18th birthday.
Contracts, Work and Business
At 18, you can legally sign contracts and other legal documents, do not need "working papers" or other permits required of minors, can work full-time and can start a 401k (retirement) plan. You can open a checking account, get a credit card or ATM card, own a car, get insurance and buy or lease an apartment or house. You can sue someone or be sued.
Tobacco and Alcohol
In most states, you can buy tobacco products at 18, though there is a recent movement to raise the legal age to buy cigarettes and other tobacco products to 19 in certain states. At 18, you cannot legally drink alcohol in the U.S. Though the legal drinking age has gone up and down over the years, in 1984, the Uniform Drinking Age Act raised the drinking age to 21 in all 50 states. In some states, when you turn 18, you can serve alcohol at work (though not in all states, and there may be conditions).
Other Legal Rights
When you turn 18, you can receive medical care, donate blood and get tattoos and piercings without parental consent or permission. You can also buy lottery tickets in most states, gamble in casinos in some states, change your name, buy adult video games or go to an X-rated movie, buy a rifle or shotgun, move out of your parents' house and be responsible for yourself. By turning 18, you are believed to have the maturity and judgment to make important decisions on your own.