Contra Costa County is in San Francisco Bay Area California. Of the 58 counties in the state, Contra Costa County ranks 50th in terms of size (514,601 acres). California's Contra Costa County has nearly 1,000 acres of residential land for sale based on recent Land Network data. The combined market value of farms and ranches for sale here was approximately $89 million. The average price of residential acreage for sale in Contra Costa County was $2 million. Browse all residential land and rural property for sale in California to find residential land and properties that suit your lifestyle needs, from existing residential homes and estates to land ready for future residential-property development.