It rises in the Gallatin National Forest in the Absaroka Range in southern Park County.

It flows north through mountainous canyons, a cataract under a natural bridge, and northwest in a widening valley past McLeod.

Other attractions in the valley include several church camps, a guest ranch, and several USFS campgrounds.

The Forest Service also maintains several guard stations, trailheads, and picnic areas in the valley.

The Placer Basin SNOTEL weather station is situated near the source of the East Boulder River, at an elevation of 8830 feet (2691 m).