Which term describes the vast lands between the Mississippi River and the Pacific Coast before 1860?

The term "Great American Desert" specifically refers to the arid region that extends from the Mississippi River to the Rocky Mountains, characterized by sparse vegetation and difficult living conditions. It was perceived as largely inhospitable to settlers during the mid-19th century, which is why it was labeled as a "desert."

This term highlights the misunderstanding of the land by many Americans at that time, as they did not recognize the agricultural potential of different parts of this vast territory. In contrast, the Oregon Territory, Texas Plains, and Frontier Lands refer to more specific areas that do not encompass the entirety of the land between the Mississippi River and the Pacific Coast. The Oregon Territory is mainly associated with the Pacific Northwest, the Texas Plains pertains to Texas, and Frontier Lands generally refers to areas of westward expansion but is not as specific as "Great American Desert" in terms of geography and perception during that era.