Idaho Falls, city (1990 pop. 43,929), seat of Bonneville co., SE Idaho, traversed by the Snake River; inc. 1900. The chief city of the extensively irrigated upper Snake valley, Idaho Falls is the prosperous commercial and processing center of a cattle, dairy, and farm region that produces potatoes, wheat, sugar beets, and alfalfa. Building materials, food products, leather goods, and electronic equipment are manufactured, and tourism is important (the city lies near several national parks and major recreational areas). Nearby Idaho National Engineering and Environmental Laboratory, a national reactor testing station, is also a principal source of employment. Idaho Falls was originally a miner's fording point over the Snake River, first settled by Mormons. The impressive Idaho Falls Mormon Temple (opened 1945) is a prominent landmark. Several annual rodeos are held in Idaho Falls.