Yellowstone National Park, which was founded in 1872, is the first and oldest national park in the United States' National Park System. In fact, Yellowstone is older than the National Park Service itself, which wasn't established until 1916.
Yellowstone is about 2,219,000 acres in size, and it covers territory in three states: Idaho, Wyoming and Montana. This park is famous for it geysers, including the well-known Old Faithful, and other natural features such as its waterfalls and colorful hot springs. Many different wild animals live in Yellowstone, including some of the few remaining wild bison in existence and large groups of wild wolves, elk and bears.