OC Bus is the transit bus service operated by the Orange County Transportation Authority (OCTA), serving every city in Orange County. Some of the lines serve the Los Angeles County border communities of Lakewood, La Mirada, Cerritos, Hawaiian Gardens, and Long Beach. As of February 2023, there are 52 routes in the system.

The Orange County Transportation Authority (OCTA) is the transportation planning commission for Orange County, California in the Los Angeles metropolitan area. OCTA is responsible for funding and implementing transit and capital projects for the transportation system in the county, including freeway expansions, express lane management, bus and rail transit operation, and commuter rail funding and oversight.