Belle Plaine, IA has a population of 2,562 and is the 9,701st largest city in the United States. The population density is 796 per sq mi which is 1357% higher than the Iowa average and 778% higher than the national average. The median age in Belle Plaine is 39 which is approximately 2% higher than the Iowa average of 38. In Belle Plaine, 64% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 80% of Belle Plaine residents were born in Iowa, 20% were born out of state, 0% were born outside of the United States and 0% were foreign born.