Indio (ĭnˈdē-ōˌ) [key], city (1990 pop. 36,793), Riverside co., SE Calif., in the Coachella Valley of the Colorado Desert, 22 ft (6.7 m) below sea level; founded 1876, inc. 1930. It is the trade and administrative center for a citrus, grape, cotton, grain, and poultry area. Indio is also the center of one of the largest date-producing areas in the United States, and the National Date Festival is held there. The area benefited from the regional growth of the electronics and aircraft industries in the 1980s and 90s, and more recently from the development of resorts and retirement communities. Joshua Tree National Park is nearby.