The population was 5,383 at the 2000 census. It is the largest borough in Snyder County. Selinsgrove is the principal city in the Selinsgrove, PA Micropolitan Statistical Area, and is also part of the larger Bloomsburg-Berwick-Sunbury, PA Combined Statistical Area.
Selinsgrove is located in the middle of the Susquehanna River Valley in Central Pennsylvania along US Route 11 & US Route 15, north of Harrisburg and about five miles (8 km) southwest of Sunbury. It is the home of Susquehanna University.