Crystal City is a city in and the county seat of Zavala County, Texas, United States. The population was 7,138 at the 2010 census. It was settled as a farming and ranching community and was a major railroad stop being 110 miles from San Antonio. Spinach became a major crop and the city has promoted itself as "Spinach Capital of the World." During World War II, a large internment camp was located here. The town is also noteworthy in the history of Mexican American political self-determination for the founding of the La Raza Unida Party.