Pima County

County of southern Arizona, USA, bordering on Sonora, Mexico; area 23,794 sq km/9,187 sq mi; population (1990) 666,900. Tucson, its seat, dominates the economy of the northeastern region. Most of the county lies in the Sonoran Desert; the Organ Pipe National Monument and the Tohono O'odham Indian Reservation (Papago Reservation) are in the western section. Several luxurious health resorts are located around Tucson. Along the Santa Cruz River, to the east, is an irrigated area producing alfalfa, citrus fruits, market garden crops, and cotton; the Egyptian-derived pima cotton takes its name from the county.