California is a home rule-class city in Campbell County, Kentucky, United States. The population was 83 at the 2020 census. California, Kentuc…California is a home rule-class city in Campbell County, Kentucky, United States. The population was 83 at the 2020 census. California, Kentucky was founded ca. 1849, and named from news reports of the contemporaneous California Gold Rush. A post office has been in operation at California since 1852. California was incorporated as a city on February 7, 1874.