Monroe, PA has a population of 663 and is the 17,790th largest city in the United States. The population density is 1,343 per sq mi which is 385% higher than the Pennsylvania average and 1382% higher than the national average. The median age in Monroe is 35 which is approximately 15% lower than the Pennsylvania average of 41. In Monroe, 51% of the population over 15 years of age are married, 99% speak English and 0% speak Spanish. 81% of Monroe residents were born in Pennsylvania, 16% were born out of state, 1% were born outside of the United States and 2% were foreign born.