If your schedule allows you to be in the vicinity of Mammoth Cave National Park on August 25th, you'll be able to go on one of the cave tour's for free in celebration of the 91st birthday of the National Park Service.
Free tours of the Discovery tour of the park will be available between 10 a.m. and 2 p.m. that day. The Discovery tour is a three-quarter-mile, self-guided tour of the cave that leads from the Historic Entrance to the Rotunda, Audubon Aveneue, and Rafinesque Hall. Rangers will be stationed along the route to provide interpretation of the geology and cave history and to answer any questions.
On August 25, 1916, President Woodrow Wilson signed the act creating the National Park Service, a new federal bureau in the Department of the Interior responsible for protecting 35 national parks and monuments. The Organic Act states:
“…the Service thus established shall promote and regulate the use of the Federal areas known as national parks, monuments and reservations…by such means and measures as conform to the fundamental purpose of the said parks, monuments and reservations, which purpose is to conserve the scenery and the national and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.”