Yellowstone National Park
It's hard to create any type of national park list without including Yellowstone. One of the most popular destinations on the NPS menu, the park is known for its wildlife and amazing natural attractions like the Old Faithful geyser. Yellowstone was the forefather of America's other national parks, and some people consider it to be the first true national park in the world. It draws large crowds during the summer, with roads to some of the geysers and scenic sites getting quite traffic-heavy. However, as with other national parks, step even a few feet off the beaten path and you'll feel like you have Yellowstone all to yourself.