History of the National Park Service

Since 1872 the United States National Park System has grown from a single, public reservation called Yellowstone National Park to include 431 natural, historical, recreational, and cultural areas throughout the United States, its territories, and island possessions. These areas include 63 National Parks as well as National Monuments, National Memorials, National Military Parks, National Historic Sites, National Parkways, National Recreation Areas, National Seashores, National Scenic Riverways, and National Scenic Trails.

Source: Wikipedia — History of the National Park Service (CC BY-SA 4.0)