States almost always considered in the US southwestern (Dark red):U.S. South, as it shared that region's history of slavery and membership in the Confederate States of America during the American Civil War. It is also unusual in having for a time been an independent nation, the Republic of Texas. The American Civil War dragged on for six more months than the rest of the nation, in the southern tip of Texas, where Mexican gold coins had displaced the worthless Confederate dollar, and smugglers profitted in the North-South trade with Mexico.
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.
Population growth in the hot, arid Southwest has depended on two human artifacts: the dam and the air conditioner. Dams on the Colorado and other rivers and aqueducts such as those of the Central Arizona Project have brought water to once-small towns such as Las Vegas, Nevada; Phoenix, Arizona; and Albuquerque, New Mexico, allowing them to become metropolises. Las Vegas is renowned as one of the world's centers for gambling, while Santa Fe, New Mexico, is famous as a center for the arts, especially painting, sculpture, and opera. Another system of dams and irrigation projects waters the California Central Valley, which is noted for producing large harvests of fruits and vegetables.