St. Clairsville, PA has a population of 78 and is the 27,482nd largest city in the United States. The population density is 2,581 per sq mi which is 831% higher than the Pennsylvania average and 2749% higher than the national average. The median age in St. Clairsville is 38 which is approximately 7% lower than the Pennsylvania average of 41. In St. Clairsville, 67% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 99% of St. Clairsville residents were born in Pennsylvania, 1% were born out of state, 0% were born outside of the United States and 0% were foreign born.