Red Oak, IA has a population of 5,547 and is the 6,045th largest city in the United States. The population density is 1,406 per sq mi which is 2473% higher than the Iowa average and 1452% higher than the national average. The median age in Red Oak is 44 which is approximately 14% higher than the Iowa average of 38. In Red Oak, 60% of the population over 15 years of age are married, 95% speak English and 5% speak Spanish. 65% of Red Oak residents were born in Iowa, 32% were born out of state, 0% were born outside of the United States and 2% were foreign born.