Alamo is an unincorporated community and census-designated place (CDP) in Contra Costa County, California, in the United States. It is located in the East Bay region of the San Francisco Bay Area. As of the 2010 census, the population was 14,750. Alamo was named by the Spanish in 1850 for the poplar trees that lined San Ramon Creek. As an unincorporated community, Alamo does not have a government of its own. Police services are provided by the Contra Costa County Office of the Sheriff.