Imperial Valley

The Imperial Valley is a fertile region in the Colorado Desert. It extends from southeastern California to northwestern Mexico. Since it was once part of the Gulf of California, most of the region is below sea level and its lowest point is at the southern shore of the Salton Sea, which is -71 m (-232 feet). On average, the area receives only 7.6 cm (3 inches) of rain annually. The Imperial Valley experiences extremely high temperatures that often reach 46°C ( 115° F) and it has a great daily temperature range. Having one of the longest growing seasons in the United States (more than 300 days), the valley can, with irrigation, support two crops a year. It was first irrigated in 1901.

Several disastrous floods on the Colorado River in 1905 and 1906 inundated the area and it was not until 1936, with the completion of Hoover Dam, that the valley was safe from floods. Approximately 404,700 hectares (1 million acres) of the valley have been irrigated, mainly by the All-American Canal. The valley is an important source of winter fruits and vegetables for the northern areas of the United States. Cotton, dates, grains and dairy products are also important. Brawley, Calexico and El Centro, all in California, are the main U.S. cities in the valley. Mexicali, Mexico is also in the valley. It is the center of Mexico's important cotton-growing district.