Rapids City, IL has a population of 1,095 and is the 14,578th largest city in the United States. The population density is 677 per sq mi which is 205% higher than the Illinois average and 647% higher than the national average. The median age in Rapids City is 42 which is approximately 12% higher than the Illinois average of 37. In Rapids City, 75% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 59% of Rapids City residents were born in Illinois, 38% were born out of state, 0% were born outside of the United States and 2% were foreign born.