American Falls is a city in and the county seat of Power County, Idaho, United States. The population was 4,457 at the 2010 census.
American Falls was a landmark waterfall on the Snake River, named after a party of American trappers whose boat went over the falls. The Wilson Price Hunt expedition in 1811 camped at the falls one night and the expedition of John C. Frémont was here in 1843. The Oregon Trail passed north of town, through the present-day reservoir. Power plants first sprang up at the falls in 1901. American Falls was the first town in the U.S. to be entirely rerelocated; it was moved in 1925 to facilitate construction of the nearby American Falls Dam. The old townsite sits at the bottom of the reservoir, northwest of the present city. A larger dam was completed in 1978, downstream from the deteriorating 1927 structure, which was later demolished.
American Falls is located at 42°46′52″N 112°51′20″W (42.781121, -112.855694), at an elevation of 4,406 feet (1,343 m).
According to the United States Census Bureau, the city has a total area of 1.69 square miles (4.38 km2), all of it land.
American Falls has a semi-arid climate (Köppen BSk).
As of the census of 2010, there were 4,457 people, 1,474 households, and 1,104 families living in the city.