The Largest Arch in Idaho - King Mountain Natural Arch Exploration

The King Mountain Natural Arch is an eighty foot high limestone arch located on the southern portion of King Mountain in Arco. Welcome to the largest natural arch in Idaho. The King Mountain Natural Arch Trail is approximately 1/2 mile long with over 1000 ft elevation gain and is generally snow free from May through mid-October.

This non-motorized trail begins by going through a wooden fence and starts uphill. I highly recommend a high clearance vehicle due to the numerous rocky sections of this road. The trail continues uphill through great basin rye grass, mountain mahogany and sagebrush. The rock formations in the area are quite breathtaking. A series of steps characterizes the steepest parts of the trail. As the trail ascends higher, the vegetation changes to Douglas fir forest which provides welcome shade over the upper parts of the trail. Nearing the top, the trail switches back and heads toward the upper platform where the arch can be seen. If you are feeling brave enough there is an old rope that continues up a steep rocky incline.