Yellowstone National Park is in the northwest region of the United States.
The park covers 3,472 square miles. Even though the official address is to the state of Wyoming, Yellowstone is actually in three states. The majority of the Park (96%) is in Wyoming. A small section of the Park (3%) to the north and northwest is in Montana. And a small section of the Park (1%) to the west is in Idaho.
Yellowstone has five entrances: north, northeast, east, south, and west. The park is enormous, which is why it’s a good idea to figure out what you want to see and know which entrance is closest to those sights.
Choose your park portal by reading Which Entrance to Yellowstone National Park Should I Take?
Yellowstone has eight developed visitor areas with visitor centers, lodging, and museums. These include: Mammoth Hot Springs, Tower-Roosevelt, Canyon Village, Fishing Bridge, West Thumb, Grant Village, Old Faithful, and Madison. Undeveloped, wild areas include Lamar and Hayden valleys. Both are wildlife-watching havens.
Other national parks are within a day or two drive from Yellowstone. May people do road-trip vacations that include multiple park. The most popular are Yellowstone plus Grand Teton National Park (Yellowstone's neighbor to the south), Yellowstone plus Glacier National Park (a day's drive to the north), and Yellowstone plus Badlands National Park, Mount Rushmore, and Devils Tower National Monument (one-to-two day's drive to the east).