Freemansburg is a borough in Northampton County, Pennsylvania. The population of Freemansburg was 2,875 as of the 2020 census. The Lehigh River, a 109-mile-long tributary of the Delaware River, flows through Freemansburg. Freemansburg is part of the Lehigh Valley metropolitan area, which had a population of 861,899 and was the 68th-most populous metropolitan area in the U.S. as of the 2020 census.