San Dimas is a city in the San Gabriel Valley of Los Angeles County, California, United States. At the 2020 census, its population was 34,924. It historically took its name from San Dimas Canyon in the San Gabriel Mountains above the northern section of present-day San Dimas.

Walnut is a city in the eastern part of Los Angeles County in the U.S. state of California. According to the 2010 census, the city had a population of 29,172, and the population was estimated to be 29,685 in 2019.