There are 13 US Post Offices in Mesa County serving a total of 103,787 residents equating to 7,984 residents per post office. It's estimated that approximately 165,656 packages are handled across the 13 county post offices annually. Mesa County is one of the 64 counties of the U.S. state of Colorado. As of the 2010 census, the population was 146,723. The county seat is Grand Junction. The county was named for the many large mesas in the area, including Grand Mesa. Mesa County comprises the Grand Junction, CO Metropolitan Statistical Area."