where is middletown, pa
Middletown, Dauphin County, Pennsylvania. Middletown is a borough in Dauphin County, Pennsylvania, United States, on the Susquehanna River, 10 miles (16 km) southeast of Harrisburg. As of the 2010 census it had a population of 8,901. It is part of the HarrisburgâCarlisle Metropolitan Statistical Area.