Diamond Bar is a city in eastern Los Angeles County, California, United States. At the 2010 census it had a population of 55,544, and in 2019 the population was estimated to be 55,720. It is named after the "diamond over a bar" branding iron registered in 1918 by ranch owner Frederic E. Lewis (1884–1963). The city features a public Los Angeles County golf course.

State Route 60 (SR 60) is an east–west state highway in the U.S. state of California. It serves the cities and communities on the eastern side of the Los Angeles metropolitan area and runs along the south side of the San Gabriel Valley. It functions as a bypass route of Interstate 10 (I-10) through the area between the East Los Angeles Interchange in Los Angeles and Beaumont. SR 60 provides a route across several spurs of the Peninsular Ranges, linking the Los Angeles Basin with the Pomona Valley and San Gabriel Valley. The highway also runs concurrently with SR 57 and I-215. Portions of SR 60 are designated as either the Pomona Freeway or the Moreno Valley Freeway.