Clayton Map
Clayton (formerly, Clayton's and Claytonville) is a city in Contra Costa County, California, United States. The population was 10,897 as of the 2010 census.
According to the United States Census Bureau, the city has a total area of 3.8 square miles (9.9 km²), all land.
Clayton is located at the foot of Mt. Diablo State Park.
Nearby cities include Lafayette, San Ramon, Martinez, Oakley, Moraga.