Contra Costa County
There are 42 US Post Offices in Contra Costa County serving a total of 1,072,175 residents equating to 25,528 residents per post office. It's estimated that approximately 1,711,311 packages are handled across the 42 county post offices annually. Contra Costa County is a county located in the state of California in the United States. As of the 2010 census, the population was 1,049,025. The county seat is Martinez. The name means \"opposite coast\" in Spanish. Contra Costa County is included in the San Francisco\u2013Oakland\u2013Hayward, CA Metropolitan Statistical Area, CA Metropolitan Statistical Area. It occupies the northern portion of the East Bay region and is primarily suburban.