The United States National Park system encompasses approximately 83.6 million acres (338,000 kmē), of which more than 4.3 million acres (17,000 kmē) remain in private ownership. The largest park is Wrangell-St. Elias National Park and Preserve, Alaska. At 13,200,000 acres (53,000 kmē) it is over 16 percent of the entire system. The smallest unit in the system is Thaddeus Kosciuszko National Memorial, Pennsylvania, at 0.02 of an acre (80 mē).
The head of state of the UnitedStates is called the President, who also serves the functions of chief executive and commander in chief of the armed forces.
As the most powerful person in the UnitedStates, a democratic republic and currently the world's only superpower, the President is sometimes referred to as "the leader of the free world," though this designation was more common during the Cold War.
Through the Department of State, the president is responsible for the protection of Americans abroad and of foreign nationals in the UnitedStates.