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city, seat (1911) of Bonneville county, southeastern Idaho, U.S., on the upper Snake River. Originally the territory of the Shoshone-Bannock and Northern Paiute Indians, it began as the Eagle Rock settlement at Taylor's Ferry (1863), later Taylor's Bridge. The town was renamed in 1890 for the low but wide (1,500 feet [460 metres]) cataract in the river (now a source of hydropower), and it developed first as a railroad division point and later as a centre of irrigated farming. The city has diversified industry, but its main sources of income are high-tech industry, agriculture (barley, potatoes), livestock, the nearby Idaho National Engineering and Environmental Laboratory (nuclear-power testing), and tourism. The Idaho Falls Mormon temple (1944) is a riverbank landmark. Inc. town, 1890; city, 1900. Pop. (1990) 43,929; (2000) 50,730.