Lone Tree is a home rule municipality in Douglas County, Colorado, United States. The city population was 10,218 at the 2010 United States Census, with an estimated population of 13,545 in 2014. Lone Tree is a part of the Denver-Aurora-Lakewood, CO Metropolitan Statistical Area.
Lone Tree is located at 39°32′56″N 104°53′33″W, on the northern border of Douglas County, directly adjacent to Arapahoe County. It is in what is called the "South Metro" area of Denver, located 18 miles (29 km) south of Denver's downtown.
According to the United States Census Bureau, the city has a total area of 9.6 square miles (24.8 km2), all of it land.