Rock Rapids, IA has a population of 2,569 and is the 9,680th largest city in the United States. The population density is 606 per sq mi which is 1009% higher than the Iowa average and 569% higher than the national average. The median age in Rock Rapids is 40 which is approximately 5% higher than the Iowa average of 38. In Rock Rapids, 76% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 52% of Rock Rapids residents were born in Iowa, 47% were born out of state, 0% were born outside of the United States and 1% were foreign born.