El Paso is the county seat of El Paso County in the U.S. state of Texas. According to the 2005 U.S. Census population estimates, the city had a population of 598,590, making it the sixth-largest city in Texas and the 21st-largest city in the United States. El Paso is second only to San Diego, California in size among all U.S. cities on the U.S.-Mexico border. Ciudad Juárez, Chihuahua lies opposite of the Rio Grande — which separates the two cities—forming a bi-national metropolitan area of 2,280,782, making it the second-largest bi-national metropolitan area on the U.S.–Mexico border.
El Paso is home to The University of Texas at El Paso. Fort Bliss, a major United States Army installation, lies to the east and northeast of the city, extending north up to the White Sands Missile Range. The Franklin Mountains extend into El Paso from the north and nearly divide the city into two sections.