Ciudad Juárez, commonly referred to as just Juárez, is the most populous city in the Mexican state of Chihuahua. It was known until 1888 as El Paso del Norte. It is the seat of the Juárez Municipality with an estimated population of 2.5 million people. Juárez lies on the Rio Grande river, south of El Paso, Texas, United States. Together with the surrounding areas, the cities form El Paso–Juárez, the second largest binational metropolitan area on the Mexico–U.S. border, with a combined population of over 3.4 million people.