San Dimas is a city in the San Gabriel Valley of Los Angeles County, California. The city historically took its name from San Dimas Canyon in the San Gabriel Mountains above the northern section of present-day San Dimas. San Dimas is bordered by the San Gabriel Mountains range to the north, Glendora and Covina to the west, La Verne to its north and east side, Pomona to its south and east side, and Walnut to the southwest.