What are the weeks or big places in the western United States?

The western United States includes parts of California, Oregon, Washington, Arizona, Nevada, Montana, Utah, Idaho, Wyoming, Colorado, New Mexico and Texas, but now the commonly used division methods include six states: North Dakota, South Dakota, Buddas, Kansas, Oklahoma and Texas. In American history, "the west" is a very uncertain concept. At first, it only refers to the area between the Appalachian Mountains and the Mississippi River. Later, with the expansion of American territory, its scope gradually expanded to include the whole area along the Pacific coast, and it was also divided into "old west", "new west" and "far west".