Mount Rushmore National Memorial commemorates 150 years of American history through the successes, setbacks, and perseverance of four visionary U.S. presidents: George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln. The memorial serves as a tribute to these leaders and is intended to inspire visitors by highlighting the nation's ideals of freedom and democracy. The memorial is a unit of the National Park Service located in the Southern Black Hills of South Dakota. The memorial welcomes over 2.4 million visitors annually and is open year-round.