Missouri Valley, IA has a population of 2,689 and is the 9,386th largest city in the United States. The population density is 832 per sq mi which is 1424% higher than the Iowa average and 819% higher than the national average. The median age in Missouri Valley is 43 which is approximately 14% higher than the Iowa average of 38. In Missouri Valley, 55% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 52% of Missouri Valley residents were born in Iowa, 47% were born out of state, 0% were born outside of the United States and 1% were foreign born.