Firestone, CO has a population of 11,709 and is the 3,481st largest city in the United States. The population density is 838 per sq mi which is 1582% higher than the Colorado average and 825% higher than the national average. The median age in Firestone is 34 which is approximately 7% lower than the Colorado average of 36. In Firestone, 70% of the population over 15 years of age are married, 90% speak English and 9% speak Spanish. 52% of Firestone residents were born in Colorado, 42% were born out of state, 1% were born outside of the United States and 4% were foreign born.