45th parallel

Overview

A classic roadside stop between Gardiner and Mammoth Hot Springs, this wooden sign marks the 45th parallel—halfway between the Equator and the North Pole. It’s a fun, two‑minute photo op along the Gardiner River and a good way to break up the drive.

What it is (and isn’t)

The sign marks the famous latitude, not the Montana–Wyoming state line. Surveying quirks mean the border doesn’t perfectly follow the 45th through here. The actual 45th parallel crosses the road roughly 0.2–0.23 miles south of the sign, but there’s no safe place to stop right at that point.

Why the sign moved

It used to sit near the Boiling River parking area, but summer congestion made that spot dicey. In 2008 the park relocated it to today’s small turnout, which is both safer and closer to the true latitude (within about 1,200 feet).

Amenities and nearby services

On-site amenities are basically just parking. There are no restrooms or water at the turnout. For facilities, aim for Mammoth Hot Springs or the town of Gardiner.

Access and seasonality

The Gardiner–Mammoth road is typically open year‑round, though many interior roads and facilities open on a staggered spring schedule. Always confirm current road and facility status before you go.

Boiling River note

Older guides tie this area to Boiling River soaking. That access has been closed in recent years—check current conditions if you’re hoping for a soak.

Best time to visit

This is a quick stop any time of day, but it’s easiest to pull in early or late when traffic is lighter. If you’re driving between the Roosevelt Arch and Mammoth, plan to snag the turnout on your way rather than attempting last‑second stops.