Explore Diamond Bar local geography, civic resources and voter guides, with dated official population and registration facts for Los Angeles County.
At a glance: Diamond Bar is an incorporated city in Los Angeles County. Population: 53,538 (California Department of Finance estimate as of January 1, 2026). Registered voters: 34,938 (California Secretary of State, as of September 4, 2026).
Diamond Bar occupies rolling hills at the southeastern edge of the San Gabriel Valley, near the junction of the Pomona and Orange freeways. Its terrain produces winding residential streets, ridgeline views, and a different pattern from the valley's flatter street grids. Pantera Park and Sycamore Canyon Park are locally recognizable outdoor destinations. The Diamond Bar Center provides a municipal setting for community events and rentals, while City Hall on Copley Drive houses administrative services. Diamond Bar incorporated on April 18, 1989, and is a general-law city with council-manager government. Its City Clerk's Office administers municipal elections, manages official records, and supports council meetings and public participation.
The City Clerk's Office links to election information, including voting districts and candidate nomination materials. Check the current materials rather than relying on an older district description.
Yes. The clerk page links to an Online Records Library covering materials such as council agendas, budgets, permits, and other city documents.
City Hall is at 21810 Copley Drive.
34,938 (California Secretary of State, as of September 4, 2026).
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