Lone Tree, CO has a population of 12,808 and is the 3,243rd largest city in the United States. The population density is 1,322 per sq mi which is 2556% higher than the Colorado average and 1360% higher than the national average. The median age in Lone Tree is 37 which is approximately 1% higher than the Colorado average of 36. In Lone Tree, 63% of the population over 15 years of age are married, 84% speak English and 5% speak Spanish. 30% of Lone Tree residents were born in Colorado, 53% were born out of state, 3% were born outside of the United States and 14% were foreign born.