Mammoth Hot Springs: 45th Parallel Bridge

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45th Parallel Bridge

Be sure to visit the 45th Parallel Bridge, located close to the Boiling River in Yellowstone National Park, where the 45th parallel of latitude runs on planet Earth.

  • Visit the 45th Parallel Bridge to see where the 45th parallel marks the midway point between the North Pole and equator
  • Swim in the Boiling River and luxuriate in the warm waters

What can I see and do at the 45th Parallel Bridge?

  • Take a Photo: Capture the moment at the 45th Parallel Bridge, which marks one point on the 45th parallel that also crosses the globe through Venice, Italy, Ottawa, Canada and Minneapolis-St. Paul, Minnesota. This is an imaginary line circling Earth halfway between the North Pole and the equator.
  • Swim in the Boiling River: The Boiling River is just one of a couple places in Yellowstone Park where folks can swim in the area's warm waters. The 140 degree springs spill into the cool Gardner River, where people have built up natural rock pools that are great for a dip anytime of year. Follow a well marked trail about .5 miles upstream from the sign to find the springs. The soaking area is closed from spring until mid-summer.

    Where is the 45th Parallel Bridge?

    The 45th Parallel Bridge is located between the Gardner River and Mammoth Hot Springs, on the park entrance road. There is a parking area right by the sign.