Nancy Run is a tributary of the Lehigh River in Northampton County, Pennsylvania, in the United States. The creek is approximately 4.1 miles (6.6 km) long and flows through Bethlehem Township and Freemansburg. The stream's watershed has an area of approximately 6.14 square miles (15.9 km2). It is classified as a Coldwater Fishery and a High-Quality Coldwater Fishery and has been home to trout and a diverse macroinvertebrate community.