Sonora (sōnōˈrä) [key], state (1990 pop. 1,823,606), 70,484 sq mi (182,554 sq km), NW Mexico, on the Gulf of California, S of Arizona. Hermosillo is the capital. Sonora is mostly mountainous, with vast desert stretches; along the gulf are low, broad coastlands. Reclamation projects on the Yaqui, Sonora, Mayo, and other rivers have opened large areas to agriculture. The most extensively irrigated of all Mexican states, Sonora is a leading national producer of cotton and wheat; other cereals and vegetables are also grown. Agriculture is highly mechanized. Cattle raising and fishing and aquaculture are important, and large quantities of shrimp are exported to the United States. Gold, silver, copper, and other metals are mined in Sonora. Power plants at Hermosillo and Guaymas have aided Sonora's rapid industrialization. Food processing and textile and automotive manufacturing are major industries, and numerous maquiladoras, low-cost foreign-owned plants which finish products for export to the United States, exist throughout the region. Nogales is the chief point of entry from the United States. Systematic Spanish exploration of Sonora, principally by Cristóbal de Oñate, began after Francisco Vásquez de Coronado's expedition in 1540. Spanish missionaries, notably Eusebio Francisco Kino, were active in colonizing the territory during the 17th cent. Originally part of Nueva Viscaya, which also included the present-day states of Chihuahua and Durango, Sonora was later united with Sinaloa; they became separate states in 1830. Sonora played a key role in the Mexican revolution against Porfirio Díaz that began in 1910.