Rancho Paso de Bartolo also called Rancho Paso de Bartolo Viejo was a 10,075-acre (40.77 km2) Mexican land grant in present-day Los Angeles County, California given in 1835 by Governor Jose Figueroa to Juan Crispin Perez.
In 1843, Bernardo Guirado, a worker at the mission, acquired 876 acres (4 km2) of Paso de Bartolo from Perez.
After the Mexican-American War, former Governor Pío Pico began purchasing pieces of the estate from the heirs of Perez, and by 1852, he acquired 8,991 acres (36 km2) of the rancho.
[6] 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.
[9] There was some legal dispute over the Guirado and Sepulveda land, and with the possible encroachment on the Rancho Santa Gertrudes grant to the south.