city, seat (1907) of Imperial county, southeastern California, U.S. It lies 120 miles (200 km) east of San Diego and 10 miles (16 km) north of Mexicali, Mexico. A desert community located some 50 feet (15 metres) below sea level, it is the largest settlement below sea level in the United States. El Centro was laid out in 1905 by W.F. Holt and developed as a commercial and transportation centre for the irrigated Imperial Valley. Agriculture is the city's primary activity, and there is some manufacturing. Geothermal energy resources based on local well drilling have been developed. The Naval Air Facility–El Centro to the north is the “winter home” of the Blue Angels (the U.S. Navy's precision flying team). The Sonny Bono Salton Sea National Wildlife Refuge, adjacent to the Salton Sea, also is north of the city. Inc. 1908. Pop. (1990) 31,384; (2000) 37,835.