Heidelberg, PA has a population of 1,321 and is the 13,435th largest city in the United States. The population density is 4,662 per sq mi which is 1542% higher than the Pennsylvania average and 5046% higher than the national average. The median age in Heidelberg is 44 which is approximately 9% higher than the Pennsylvania average of 40. In Heidelberg, 49% of the population over 15 years of age are married, 95% speak English and 3% speak Spanish. 88% of Heidelberg residents were born in Pennsylvania, 10% were born out of state, 1% were born outside of the United States and 2% were foreign born.