Pine Run is a tributary of the North Branch Neshaminy Creek, part of the Delaware River watershed. Pine Run flows entirely in Bucks County, Pennsylvania, rising in Plumstead Township, passing through Buckingham Township and New Britain Township, meeting its confluence with the North Branch in the Borough of Chalfont.
Pine Run powered two of the earliest mills in central Bucks County; Dyers Mill at Dyerstown and Butler Mill at Chalfont.
The watershed of Pine Run is , its confluence is at the North Branch Neshaminy Creek's 0.45 river mile. The Geographic Name Information System I.D. is 1183891, U.S. Department of the Interior Geological Survey I.D. is 02790.
Rising from an unnamed pond near Landisville in Plumstead Township at an elevation of , it flows to the southwest through Buckingham Township where it meets the Pine Run Dam and lake, then through New Britain Township, then finally into the Borough of Chalfont where it meets with the North Branch of the Neshaminy at an elevation of . Pine Run has a total length of resulting in an average slope of .
Pine Run flows within the Stockton Formation, bedrock laid down during the Triassic, consisting of arkosic sandstone, sandstone, shale, siltstone, and mudstone. Then as it enters Chalfont, it enters the Lockatong Formation, also from the Triassic, consisting of argillite, black shale, limestone, and shale.