Minimum legal age varies for all kinds of grownup things. Alcohol, tobacco, and cannabis can be 18, 19 or 21, depending on state, province or territory.
Learning to drive is between 14 and 16, with agricultural states tending to allow driving at a younger age. The age of consent is 16 in most US states and throughout Canada. At 18, you can vote and even run for political office in both countries.