Yellowstone and Grand Tetons national parks are located in Wyoming. Yellowstone is the first national park in the United States, and it is also one of the largest national parks in the world.The park covers more than 2 million acres, and it is home to a variety of wildlife, including bison, elk, bears, and wolves. The geothermal features of Yellowstone are also well-known, and they include the Old Faithful geyser.