At the top of the Beartooth Pass, the world drops away. You stand at about 10,950 feet on a broad, treeless plateau of granite, tundra and tiny lakes, with snowfields clinging to the shaded slopes even in midsummer. The air is thin enough that you will notice it when you walk, and the sky is a deep, dark blue. In every direction, the rock is old: the Beartooth range is made of some of the oldest rock in North America, nearly three and a half billion years old in places, and the landscape has the bare, scoured look of something that has seen a very long time pass.
The plateau supports a fragile alpine ecosystem. Low cushions of flowers, sedges and dwarf willow cling to the ground, mountain goats graze on the slopes, and marmots and pikas watch from the rocks. In summer, the wildflowers are astonishing, and short as the season is, the colours are intense. Hikers set out from pullouts along the road, though at this altitude any walk is slow and demanding, and the weather can change in minutes.
The highway crosses the border between Montana and Wyoming here, and in fact it dips in and out of both states along this high stretch. The pass is closed in winter, usually from mid-October, and a fall of snow can come any month of the year, so be ready for cold, wet conditions. Thunderstorms build on summer afternoons and lightning is a real danger on the exposed ridge, so make a point of crossing early and be off the top by noon.
On the bike, the experience is exhilarating and demanding. The road is wide and well engineered, with big, open corners and a surface that is generally smooth, but it has steep drops, little in the way of guardrail in places and frost damage that appears each spring. Wind can be fierce on the plateau. Tourists and drivers of large vehicles often drive slowly and stop abruptly, so keep your distance.
There are no services at the summit, and the nearest fuel is a long way off in either direction. Carry water, a warm layer and gloves, and take your time. Do not be surprised if you find yourself pulling over every few minutes, because the views are enormous, and the sense of height is hard to describe until you are there.