Bethlehem Township is a township in Northampton County, Pennsylvania, United States. The population of Bethlehem Township was 23,730 at the 2010 census. It is a suburb of Bethlehem and is part of the Lehigh Valley metropolitan statistical area, which had a population of 861,899 and was the 68th-most populous metropolitan area in the U.S. as of the 2020 …Bethlehem Township is a township in Northampton County, Pennsylvania, United States. The population of Bethlehem Township was 23,730 at the 2010 census. It is a suburb of Bethlehem and is part of the Lehigh Valley metropolitan statistical 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.