Upper St. Clair, PA has a population of 19,521 and is the 2,230th largest city in the United States. The population density is 1,988 per sq mi which is 617% higher than the Pennsylvania average and 2095% higher than the national average. The median age in Upper St. Clair is 44 which is approximately 9% higher than the Pennsylvania average of 41. In Upper St. Clair, 73% of the population over 15 years of age are married, 90% speak English and 1% speak Spanish. 65% of Upper St. Clair residents were born in Pennsylvania, 25% were born out of state, 1% were born outside of the United States and 9% were foreign born.