There are 40 US Post Offices in Hillsborough County serving a total of 948,342 residents equating to 23,709 residents per post office. It's estimated that approximately 1,513,660 packages are handled across the 40 county post offices annually. Hillsborough County is a county located in the U.S. state of Florida. As of the 2010 census, the population was 1,229,226, making it the fourth-most populous county in Florida. Its county seat and largest city is Tampa. Hillsborough County is included in the Tampa\u2013St. Petersburg\u2013Clearwater, FL Metropolitan Statistical Area."