The Hillsborough River is a river located in the state of Florida in the United States. It arises in the Green Swamp near the juncture of Hillsborough, Pasco and Polk counties, and flows 60 miles (97 km) through Pasco and Hillsborough Counties to an outlet in the city of Tampa on Hillsborough Bay. It includes 4 nature trails extending for over 7 miles (11 km), making it popular among hikers. The name Hillsborough River first appeared on a British map in 1769. At the time, the Earl of Hillsborough was the British Secretary of State for the Colonies, and thus controlled the pensions of the surveyors working in the American colonies, which included East Florida.