Thorndale, PA has a population of 3,824 and is the 7,648th largest city in the United States. The population density is 2,073 per sq mi which is 648% higher than the Pennsylvania average and 2188% higher than the national average. The median age in Thorndale is 35 which is approximately 14% lower than the Pennsylvania average of 41. In Thorndale, 48% of the population over 15 years of age are married, 90% speak English and 1% speak Spanish. 70% of Thorndale residents were born in Pennsylvania, 19% were born out of state, 0% were born outside of the United States and 11% were foreign born.