The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States. Its exact boundaries are not officially defined, but attempts to do so generally include Arizona and New Mexico as the core of the region. Adjacent portions of California, Colorado, Nevada, and Utah are also sometimes included. Oklahoma and Texas may also be included, particularly the trans-pecos "horn" portion of the state(i.e. the far western extension of the state of the state south of the New Mexico border, but west and north of the Pecos and Rio Gande Rivers). The largest cities by metropolitan area are Phoenix, Las Vegas, El Paso, Albuquerque, and Tucson. Before 1848, in the historical region of Santa Fe de Nuevo México as well as parts of Alta California and Coahuila y Tejas, settlement was almost non-existent outside of Nuevo México's Pueblos and Spanish or Mexican municipalities. Much of the area had been a part of New Spain and Mexico until the United States acquired the area through the Treaty of Guadalupe Hidalgo in 1848 and the smaller Gadsden Purchase in 1854.
Given this paragraph about the Southwestern United States, name the largest cities in that area
The largest cities in the Southwestern United States are Phoenix, Las Vegas, El Paso, Albuquerque, and Tucson.