Rancho San Jacinto Viejo was a 35,503-acre (143.68 km2) Mexican land grant in present-day Riverside County, California given in 1842 by Governor Pro-tem Manuel Jimeno to José Antonio Estudillo.[1] At the time of the US Patent, Rancho San Jacinto Viejo was a part of San Diego County. The County of Riverside was created by the California Legislature in 1893 by taking land from both San Bernardino and San Diego Counties. The grant encompassed present-day Hemet and San Jacinto.[2]