Waterloo, city (1990 pop. 66,467), seat of Black Hawk co., NE Iowa, on the Cedar River; inc. 1868. Originally a center for sawmills and flour mills, Waterloo is a trade and industrial center in a farm and livestock area. The city's chief industries are meatpacking, soybean processing, and the manufacture of farm machinery, plastics, fabricated metal products, transportation equipment, and apparel. The National Dairy Cattle Congress is held there each September. A 10-acre (4-hectare) replica of the island where the protagonist of Daniel Defoe's Robinson Crusoe was shipwrecked has been built in the Cedar River at Waterloo.