The Imperial Valley ( or Valle Imperial) of Southern California lies in Imperial and Riverside counties, with an urban area centered on the city of El Centro. The Valley is bordered by the Colorado River to the east and, in part, the Salton Sea to the west. Farther west lies the San Diego and Imperial County border. To the north is the Coachella Valley region of Riverside County, which together with Imperial Valley form the Salton Trough, or the Cahuilla Basin, also the county line of Imperial and Riverside counties, and to the south the international boundary with Mexico.
The culture of the area blends those of the United States and Mexico, due to its regional history and geographic location along the international border. The Imperial Valley economy is based on agriculture.
Imperial Valley was named by the Imperial Land Company, in the hopes of attracting settlers. It is now the home of the El Centro metropolitan area. Locally, the terms "Imperial Valley" and "Imperial County" are used synonymously. Imperial Valley is also called Lithium Valley, because of its rich supply of lithium, used to power electric vehicles, cameras, etc.
Geography
The Imperial Valley extends southward for from the southern end of the Salton Sea into Mexico. Part of a trough stretching from the Coachella Valley to the Gulf of California, it is almost entirely below sea level— below at the edge of the Salton Sea. Its hot desert climate is characterized by daily temperature extremes. It was once part of the Gulf of California, from which it was cut off by the dam-like deposits of the Colorado River Delta Fan as it carved out the Grand Canyon. Bordered by sand dunes and barren mountains, it was uninhabited until 1901, when the Imperial Canal was opened and diverted Colorado River water into the valley through Mexico. Floodwaters in 1905–07 destroyed the irrigation channels and created the Salton Sea now filled by the New River and irrigation run-off. The rivers in the southern part of the Salton Sea river basin flow south to north.
The valley is bordered by the Colorado River to the east and, in part, the Salton Sea to the west. Farther west lies the border with San Diego County and to the south the international boundary between the US state of California and Baja California, Mexico. To the north is the boundary with Riverside County and the Coachella Valley, which with the Imperial Valley form the "Cahuilla Basin" or the "Salton Trough".
El Centro is the largest industrial center of the Imperial Valley, being the center of shipping exports as well as being home to retail, transportation, wholesale, and agricultural industries. There are also two international border crossings nearby for commercial and noncommercial vehicles. The city's population was 37,835 at the 2000 census and 42,598 at the 2010 census. The city is below sea level and the largest city in the United States below sea level. Fifty percent of the jobs in El Centro come from the service and retail sector.
Climate
The Imperial Valley often has summer temperatures well over , but from late October until mid-April the temperature is relatively mild and sometimes low. During winter months the Valley averages more than eight hours of sunshine a day, receiving the most sunlight of any place in the United States.
Historically, the lowest minimum temperature ever recorded in the Imperial Valley was on January 22, 1937. The highest maximum temperature ever recorded was on July 28, 1995. The lowest maximum temperature was , recorded on January 24, 1949, and the highest minimum temperature was on June 30, 1946. The highest monthly mean temperature was , recorded in August 1969 and the lowest mean temperature was in February 1939.
The 85-year average annual rainfall is with June being the driest month. The only recorded snowfall in the Valley occurred on December 12, 1932. Snow began falling at 8:45 p.m. and by 5 a.m. the next day had been recorded. In the southwest portion of Imperial Valley, of snow was reported that day. This was the only snowfall on record to cover the entire valley.