(CNN) – Monday marks the 98th anniversary of the National Park Service.
President Woodrow Wilson signed the Organic Act, which created the Park Service on Aug. 25, 1916.
Following the establishment of Yellowstone, more than 401 national parks have been created in the United States, with more than 20,000 National Park Service employees.
In addition to parks, the National Park Service also maintains dozens of monuments and military sites.
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