Bethlehem, PA has a population of 75,110 and is the 470th largest city in the United States. The population density is 3,932 per sq mi which is 1319% higher than the Pennsylvania average and 4240% higher than the national average. The median age in Bethlehem is 35 which is approximately 13% lower than the Pennsylvania average of 41. In Bethlehem, 44% of the population over 15 years of age are married, 75% speak English and 19% speak Spanish. 55% of Bethlehem residents were born in Pennsylvania, 29% were born out of state, 8% were born outside of the United States and 8% were foreign born.