Washington Boro is a census-designated place (CDP) in Manor Township, Lancaster County, Pennsylvania, United States, along the Susquehanna River.

Due to the decline of river trade and jobs, the Borough of Washington was dissolved politically, effective December 31, 1973, becoming part of Manor Township.

[4] Washington Boro is located in western Lancaster County, in the northwestern corner of Manor Township.

The Susquehanna in this area is impounded by the Safe Harbor Dam 7 miles (11 km) to the southeast, forming Lake Clarke.

[5] Pennsylvania Route 441 has its southern terminus in Washington Boro and leads north (upriver) 4 miles (6 km) to Columbia.