Underwood, MN has a population of 391 and is the 20,988th largest city in the United States. The population density is 684 per sq mi which is 1005% higher than the Minnesota average and 655% higher than the national average. The median age in Underwood is 42 which is approximately 12% higher than the Minnesota average of 38. In Underwood, 68% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 71% of Underwood residents were born in Minnesota, 28% were born out of state, 1% were born outside of the United States and 0% were foreign born.