Littleton, CO has a population of 45,072 and is the 911th largest city in the United States. The population density is 3,551 per sq mi which is 7032% higher than the Colorado average and 3820% higher than the national average. The median age in Littleton is 42 which is approximately 14% higher than the Colorado average of 36. In Littleton, 56% of the population over 15 years of age are married, 90% speak English and 6% speak Spanish. 41% of Littleton residents were born in Colorado, 51% were born out of state, 1% were born outside of the United States and 7% were foreign born.