Wheaton, city, seat of DuPage County, northeastern Illinois, a residential community near Chicago; incorporated as a city 1890. Wheaton College (1860), the DuPage County Historical Museum, and a children's museum are here; the birthplace of the industrialist Elbert H. Gary is nearby. The community was settled in the 1830s and named for one of its pioneer families. Population 43,043 (1980); 51,464 (1990); 55,416 (2000).