What is a frontier? And how do we understand this term in the North American context?

1. Frontier is a transit zone where explorers, pioneers, and settlers come.

2. In America is considered to be a free land where the settlement is very low, only two persons per square mile.

Explanation:

Generally speaking, it is the region on the border of the settled area. The population that represents this movement of frontiers usually moves from east to west.

The best example for frontier is the border that separates Canada and the USA.