Coming of age
In the United States, teenagers are allowed to drive at 16 in all states except New Jersey, which requires drivers to be 17 and older, and sometimes receive the responsibility of owning their own car. Teenagers may drive at age 15 in Idaho and Montana. At 16, teenagers are also old enough to donate blood and work in most establishments. At 18 one is legally considered an adult and can vote and join the military. The legal age for purchasing and consuming alcohol and recreational marijuana, the latter of which is only legal in the District of Columbia, Colorado, Oregon, Washington, California, Hawaii, Massachusetts, Nevada, and Alaska, is 21. The legal age for purchasing and consuming tobacco products is 18 in most states; 19 in Alabama, Alaska and Utah; and 21 in California, New Jersey, Oregon, Hawaii and Maine. Multiple localities have also raised the minimum purchase age independent of state laws.
American juvenile justice system
Many advocates argue that the juvenile system should extend to include youth older than 18 (the age that most systems use as a cut-off). Research in neurobiology and developmental psychology show that young adults' brains do not finish developing until their mid-20s, well beyond the age of criminal responsibility in most states. Other non-criminal justice systems acknowledge these differences between adults and young people with laws about drinking alcohol, smoking cigarettes, etc.