Selinsgrove, PA has a population of 5,810 and is the 5,868th largest city in the United States. The population density is 3,173 per sq mi which is 1045% higher than the Pennsylvania average and 3402% higher than the national average. The median age in Selinsgrove is 27 which is approximately 34% lower than the Pennsylvania average of 41. In Selinsgrove, 36% of the population over 15 years of age are married, 94% speak English and 3% speak Spanish. 63% of Selinsgrove residents were born in Pennsylvania, 34% were born out of state, 1% were born outside of the United States and 3% were foreign born.