Contra Costa County is a county located in the U.S. state of California. As of the most recent data available, the county has a population of approximately 948,816 people, with a population density of about 317.80 persons per square mile.
The county spans a total land area of 720.00 square miles (1,865.00 square kilometers). The administrative center and county seat is Martinez, which often serves as a hub for local governance and services. The largest city within the county by population is Concord.
Geographically, Contra Costa County experiences varied elevations, with its highest point at Tassajara 713 ft and its lowest point at Brentwood 0 ft. The region operates in the UTC-8.