<Tr> <Th> States </Th> <Td> Alaska Arizona California Colorado Hawaii Idaho Montana Nevada New Mexico Oregon Utah Washington Wyoming </Td> </Tr> <P> The Western United States, commonly referred to as the American West, the Far West, or simply the West, traditionally refers to the region comprising the westernmost states of the United States . Because European settlement in the U.S. expanded westward after its founding, the meaning of the West has evolved over time . Prior to about 1800, the crest of the Appalachian Mountains was seen as the western frontier . </P> <P> Since then, the frontier generally moved westward and eventually, the lands west of the Mississippi River came to be referred to as the West . Though no consensus exists, even among experts, for the definition of the West as a region, the U.S. Census Bureau's definition of the 13 westernmost states includes the Rocky Mountains and the Great Basin to the West Coast, and the outlying states of Hawaii and Alaska . </P> <P> The West contains several major biomes . It is known for arid to semi-arid plateaus and plains, particularly in the American Southwest--forested mountains, including the major ranges of the American Sierra Nevada and Rocky Mountains--the massive coastal shoreline of the American Pacific Coast--and the rainforests of the Pacific Northwest . </P>

Where does the west start in the us