Sumner, IA has a population of 2,205 and is the 10,477th largest city in the United States. The population density is 899 per sq mi which is 1546% higher than the Iowa average and 892% higher than the national average. The median age in Sumner is 42 which is approximately 10% higher than the Iowa average of 38. In Sumner, 67% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 88% of Sumner residents were born in Iowa, 11% were born out of state, 1% were born outside of the United States and 1% were foreign born.