In addition to objects that have been preserved because of the information they convey about past human activities in the region, the parks’ historical resources include dozens of sites and structures listed on the National Register of Historic Places and many others that are eligible for inclusion. Most of these places, such as the White Grass Ranch in Grand Teton National Park, are of interest because of their significance in architectural or park history, but archeological sites such as Obsidian Cliff in Yellowstone and the tipi rings in Bighorn Canyon are associated with American Indian use that pre-dates the arrival of the first park visitors. The need to protect and understand the importance of all of these resources affects how the parks are managed today.