Hillsborough County is a county located in the U.S. state of Florida. The 2000 population was 998,948. As of 2007, the Planning Commision of Hillsborough County, Florida counted a population estimate for Hillsborough County, Florida at 1,204,770. Its county seat is Tampa, Florida. Hillsborough County is the largest county in the Tampa-St. Petersburg-Clearwater Metropolitan Statistical Area History

Hillsborough County was created on January 25, 1834 from Alachua and Monroe counties.  It was named for Wills Hill, Viscount Hillsborough of England. The county's boundaries of 1834 included the present-day counties of Charlotte, DeSoto, Hardee, Manatee, Pasco, Pinellas, Polk and Sarasota.