Major cities located in the southwestern region of the continental United States include Denver, Colorado; Phoenix, Arizona; and Las Vegas, Nevada. Other cities include San Francisco, Los Angeles and Oakland, California; Santa Fe, New Mexico; and Salt Lake City, Utah.
The American Southwest, by the most common definition, includes California, Utah, Nevada, New Mexico, Colorado and Arizona. More broad definitions also include Oklahoma and Texas. Most of these states were once part of the Viceroyalty of New Spain and were part of Mexico until the Mexican-American war and Gasden Purchase of 1853.
In the 19th century, the "Old Southwest" also included Alabama, Mississippi, Tennessee, Kentucky, Arkansas and Louisiana. Once Texas became a state, it was also considered part of this region. The history of the new Southwest gives it a much different feel and connotation than the "Old Southwest" or current southeast, but much of the American Indian heritage found in the current southwest is due to the American Indians who moved west from the southeastern United States. Many of the American Indian tribes in Texas and Oklahoma became allies of the Confederacy during the American Civil War. Some citizens of Texas and Oklahoma still identify themselves as southerners instead of westerners.