El Paso is the county seat of El Paso County, Texas, United States, and lies in far West Texas. As of July 1, 2013, the population estimate from the U.S. Census was 674,433, making it the 19th most populous city in the United States. Its U.S. Wikipedia

Tucson is a city in and the county seat of Pima County, Arizona, United States, and home to the University of Arizona. The 2010 United States Census puts the city's population at 520,116, while the 2013 estimated population of the entire Tucson metropolitan area was 996,544. Wikipedia