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).