Norwalk, IA has a population of 9,944 and is the 3,950th largest city in the United States. The population density is 890 per sq mi which is 1529% higher than the Iowa average and 882% higher than the national average. The median age in Norwalk is 36 which is approximately 4% lower than the Iowa average of 38. In Norwalk, 65% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 83% of Norwalk residents were born in Iowa, 16% were born out of state, 0% were born outside of the United States and 1% were foreign born.