Mount Rushmore’s summer temperatures can reach as high as 100 degrees F, and winter high temps can sometimes only reach 20 F. Geographically, the granite that the famous sculpture is composed of is part of a rock formation that is among the oldest in the western United States. The setting of Mount Rushmore —the Black Hills — is high country, at 5,725 feet above sea level. As for Mount Rushmore’s background, it was an effort of fundraising and engineering that lasted for years, reaching completion in late 1941 just days before the U.S. entered World War II.