Rancho Santa Rosa was a 47,815-acre (193.50 km2) Mexican land grant in present day Riverside County, California given in 1846 by Governor Pio Pico to Juan Moreno.

[1] At the time of the US patent, Rancho Santa Rosa was a part of San Diego County.

[5] With the cession of California to the United States following the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored.

Flood events that twice destroyed the railroad connection of the California Southern Railroad with San Diego, cutting economical transportation to and from his ranch and development projects at Linda Rosa.

In 1964, the Vails sold the ranch to the Kaiser Steel Company, which master-planned Rancho California - the communities that today comprise the cities of Temecula and Murrieta.