Fort Collins, CO has a population of 157,251 and is the 160th largest city in the United States. The population density is 2,812 per sq mi which is 5548% higher than the Colorado average and 3004% higher than the national average. The median age in Fort Collins is 29 which is approximately 20% lower than the Colorado average of 36. In Fort Collins, 45% of the population over 15 years of age are married, 90% speak English and 5% speak Spanish. 40% of Fort Collins residents were born in Colorado, 53% were born out of state, 1% were born outside of the United States and 6% were foreign born.