Massacre Rocks State Park, Idaho.
Located along the Snake River West of American Falls, Massacre Rocks State Park features a famous configuration of boulders along the south bank of the Snake River, known as Massacre Rocks, “Gate of Death,” or “Devil’s Gate.”
A famous spot along the Oregon Trail and California Trail during the mid-19th century, emigrants gave this name to the narrow passage through the rocks, out of fear of possible ambush by Native Americans. According to emigrant diaries, settlers in five wagons clashed with Shoshone just East of the rocks on August 9 and 10, 1862. Ten emigrants died in the fight, which involved four wagon trains. The skirmishes took place East of the park and not at Devil’s Gate as commonly believed, but the undeserved name stuck.
Settlers and the natives used the area for generations because the Snake River is accessible and relatively gentle in this part of its run. The violent episodes were the exception, not the rule.
The rocks are all that’s left of an extinct volcano. Wagon trains often used them as campsites along the trail. Many emigrants carved their names and dates on the rock face, which is now protected by a shelter. The actual passage through the rocks is now Interstate 86 along the South edge of the park.
Geologically, the park formed during repeated volcanic activity on the Snake River Plain. The rocks were deposited in their present location at the end of the last ice age, about 14,500 years ago, during the catastrophic Bonneville Flood, when much of Lake Bonneville surged down the Snake River. A notch in the cliff on the North bank of the Snake, opposite the park, was the site of an ancient waterfall from a side channel of water after the flood.
Ruts of the Emigrant Trail near Massacre Rocks.
The 995-acre park also includes a visitor’s center that describes its history and geology. Massacre Rocks State Park offers access to the Snake River and a 50-unit campground with water and electrical hookups for RVs, picnic areas, restrooms, and hot showers. Along the foot trails, you can see remnants of the original Oregon Trail on the South side of Interstate 86.
Contact Information:
Massacre Rocks State Park
10 miles West of American Falls (off I-86)
3592 N. Park Lane
American Falls, Idaho 83211
208-548-2672
©Kathy Alexander/Legends of America, updated September 2026.
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