July 14th, 2016 brings us 42-days away from the National Park Service Centennial. In this edition of the #CentennialCountdown we go back 42-years to 1974. When 10-units including Big Cypress National Preserve, Big South Fork National River, Big Thicket National Preserve, Boston National Historic Park, Chamizal National Memorial, Clara Barton National Historic Site, Knife River National Historic Site, Lyndon B. Johnson Memorial Grove, Martin Van Buren National Historic Site, Roger Williams National Monument were all added to the National Park system.
