​OELWEIN, a city of Fayette county, Iowa, U.S.A., in the N.E. part of the state, about 132 m. N.E. of Des Moines. Pop. (1890) 830; (1900) 5142, of whom 789 were foreign-born; (1910 U.S. census) 6028. It is served by the Chicago, Rock Island & Pacific and the Chicago Great Western railways, the latter having large repair shops here, where four lines of its road converge. Oelwein was named in honour of its founder, August Oelwein, who settled here in 1873; it was incorporated in 1888, and chartered as a city in 1897.