Diamond Bar is a city in eastern Los Angeles County, California, United States. The population was about 60,360 as of January 1, 2008. It is named after the "diamond over a bar" branding iron registered in 1918 by ranch owner Frederick E. Lewis. Located at the junction of the Pomona and Orange freeways, Diamond Bar is primarily a residential city with shopping centers interspersed within the city. The city features a public Los Angeles County golf course. Diamond Bar has the first hydrogen fueling station to be built in Southern California, near the South Coast Air Quality Management District (AQMD) building.