The migration of America west word is also called?

This expansion began with the Louisiana Purchase in 1803. The president Thomas Jefferson bought the territory from the French for $15 million, and worked in the creation of an expansionist mentality. As a result this migration is also called Westward Expansion.

Explanation:

Westward expansion, the 19th-century movement of settlers into the American West, began with the Louisiana Purchase and was fueled by the Gold Rush, the Oregon Trail and a belief in "manifest destiny."