What was the west of Mississippi River called I am the 1800s?

In the 1800s, the region west of the Mississippi River was often referred to as the "West" or "Western Frontier." This area was largely characterized by its vast landscapes, including prairies, mountains, and deserts, and it was seen as a land of opportunity for settlers and pioneers. The U.S. government promoted westward expansion through policies like the Homestead Act, and this region became central to the concept of Manifest Destiny. It included territories that would later become states such as Texas, California, and Oregon.