Placer County Transit is the operator of mass transportation for western Placer County, California, excluding the city of Roseville, which has its own public transit system. In addition to six local routes, Placer County Transit also operates the Lincoln School Tripper in Lincoln, California, a bus supplement during school days, and the Placer Commuter Express, a commuter bus service between Downtown Sacramento and the Colfax Amtrak station. In addition to their fixed route service, Placer County Transit also operates Dial-a-ride services in local communities.

Placer County, officially the County of Placer, is a county located in the U.S. state of California. As of the 2020 census, the population was 404,739. The county seat is Auburn.