El Sobrante takes its name from Rancho El Sobrante, "surplus" land situated between existing ranchos that in 1841 was granted by the government of Mexico to brothers Juan Jose and Victor Castro. El Sobrante's downtown is actually within Rancho San Pablo, an earlier Castro family grant. The Rancho El Sobrante boundary lies 1/4 mile east of and parallel to Appin Way. By the late 1800s, the Castros had lost or sold most of their land. Victor Castro's son, Patricio, continued ranching for most of his life on 100-acres along Castro Ranch Road.