Harrisburg Run is a 3.41 mi (5.49 km) long first-order tributary to Foster Brook.

[2] This is the only stream of this name in the United States.

[1] Harrisburg Run rises in Harrisburg, a small hamlet in the southwest corner of the town of Allegany in Cattaraugus County, New York, and then flows southwest in McKean County, Pennsylvania to meet Foster Brook about 0.5 miles (0.80 km) west of Derrick City, Pennsylvania.

Harrisburg Run drains 4.02 square miles (10.4 km2) of area, receives about 45.2 in/year (115 cm/year) of precipitation, and is about 92.47% forested.

[3]