Admittedly it's been a long time since this was relevant to me, so this may have changed, but where and when I grew up in the US you could get a learner's permit (unlimited driving with another qualified driver in the car) at 15 yrs and 9 mos, then a full license (able to drive by yourself and transport anyone over 18) at, I think, 16 and 6 mos. At 18 the restrictions on whom you could transport disappeared, but I've never heard of anyone paying attention to or enforcing those rules anyway.

There may also have been a restriction about driving after midnight, but I don't recall for sure.