The Southwestern United States - commonly referred to as the American Southwest or simply The Southwest - is a region of the western United States, warmer than the northern states and drier than the eastern states. Its population is less dense than neighboring areas (even its cities have relatively low population density), and with significant Spanish American, Mexican American, and American Indian populations, it is also more ethnically varied than neighboring areas.

Most of the Southwest once belonged to Spain or Mexico but ownership was ceded to the United States after the Mexican-American War of 1846-48, with the Gadsden Purchase of 1853 following. The Treaty of Guadelupe Hidalgo defines sovereignty over this region, which some Mexican groups protest by planting their flags on American soil and seek to overturn by flooding the borders today. The land was settled by Confederates in Arizona Territory (CSA) and Union Mormons in the State of Deseret.

Contained within this region is the Desert Southwest consisting mainly of Arizona, New Mexico, Nevada, Texas and Oklahoma. Other states, or more accurately, parts of other states can be considered part of the Southwest, although the precise definition varies widely. Generally, people from the Eastern United States are more prone to consider Texas and Oklahoma part of the Southwest, while people from California, Arizona, and New Mexico are likely to consider most of Texas, perhaps with the exception of far western Texas (e.g., El Paso), to be part of the South.


Phoenix, in the center of the southwest, ranks among the United States' ten largest cities. San Antonio ranks in the top ten as well, with Fort Worth in the top 20. Many of the urban areas in this region (e.g., Las Vegas, Phoenix and Fort Worth) have witnessed some of the fastest population growth in the United States over the past decade.

This region contains many Indian reservations including the Navajo, Apache, Hopi, Zuni and Pueblo people.


This region is known for its bold art. Tex Mex cuisine was popularized in South Texas (San Antonio), although more traditional Southwestern cuisine can be found west of Texas. Mexican heritage continues to exert a strong influence on the U.S. Southwest, which is a convenient place to settle for immigrants (legal or illegal) from farther south. The regional population is growing rapidly, with Arizona in particular rivaling the southern states as a destination for retired Americans in search of a warm climate.