Mill Run may refer to a geographic feature in the United States:
Streams Mill Run (Neshannock Creek tributary), a stream in Mercer County, Pennsylvania Mill Run (South Branch Potomac River tributary), a stream in Hampshire County, West Virginia Mill Run (Susquehanna River tributary), a stream in Wyoming County, Pennsylvania Mill Run (Trent River tributary), a stream in Jones County, North Carolina
Communities Mill Run, Blair County, Pennsylvania, a census-designated place Mill Run, Fayette County, Pennsylvania, an unincorporated community near the Frank Lloyd Wright "Fallingwater" Mill Run, Pocahontas County, West Virginia, a ghost town in Pocahontas County, West Virginia Mill Run, Tucker County, West Virginia, a ghost town in Tucker County, West Virginia
See also Mill Run Playhouse (aka Mill Run Theatre), a theater in the round in Niles, Illinois Mill Run Wind Energy Center, a wind farm in Fayette County, Pennsylvania Run of the Mill, a song by George Harrison