Lonetree (also Lone Tree or Steele) is a ghost town in Chouteau County, Montana, United States. Founded circa 1885, it is located at (47.5416396, -110.2840931), at an altitude of 3,123 feet (952 m). For nearly thirty years Lonetree possessed a post office, which was opened under the name of Steele on March 9, 1888; its name was changed to Lonetree on May 15, 1914. It bore this name for less than a year before closing on March 31, 1915.
The entire community of Lonetree was added to the National Register of Historic Places on September 11, 1980.