Monroe, IA has a population of 1,875 and is the 11,406th largest city in the United States. The population density is 1,107 per sq mi which is 1926% higher than the Iowa average and 1122% higher than the national average. The median age in Monroe is 39 which is approximately 2% higher than the Iowa average of 38. In Monroe, 66% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 84% of Monroe residents were born in Iowa, 16% were born out of state, 0% were born outside of the United States and 0% were foreign born.