American Falls, Idaho

American Falls was a landmark waterfall on the Snake River, named after a party of American trappers whose boat went over the falls. The Oregon Trail passed north of town, through the present-day reservoir. Power plants first sprung up at the falls in 1901. American Falls was the first town in the U.S. to be entirely relocated; it was moved in 1925 to facilitate construction of the nearby dam. The old town site sits at the bottom of the reservoir, northeast of the present city. A larger dam was completed in 1978, downstream from the deteriorating 1927 structure, which was later demolished. The reservoir is popular for boating and beach play.

According to diaries of emigrants, settlers in five wagons clashed with Shoshoni Indians just east of these massive rocks along the Snake River on August 9–10, 1862. Ten emigrants died in the skirmish, which involved four wagon trains. The area came to be feared by pioneers that followed and the name continues to this day. The rocks were deposited 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. Lake Bonneville was a prehistoric pluvial lake that covered much of North America's Great Basin region, present-day Utah and into Idaho and Nevada.