Washington Run is a long 2nd order tributary to the Youghiogheny River in Fayette County, Pennsylvania, United States.
Washington Run rises about 1 mile west of Curfew, Pennsylvania, and then flows north and turns east to join the Youghiogheny River across from Layton.
Washington Run drains of area, receives about 41.9 in/year of precipitation, has a wetness index of 353.54, and is about 51% forested.