Casa Blanca, formerly known to the Mexicans as La Tierra Amontonada (The Land Piled Up), named for the Hohokam ruin mound nearby, was one of the Pima Villages on the Gila River in what was then part of the state of Sonora, Mexico. It was encountered by the American expedition of Stephen W. Kearny in 1846 and later by Americans on their way to California on the Southern Emigrant Trail during the California Gold Rush. Following the Gadsden Purchase the Pima Villages became part of New Mexico Territory. In 1857, the San Antonio-San Diego Mail Line passed through the village on the way between Maricopa Wells and Tucson.