This child group collects United States Railroads members headquartered or historically based in the East North Central Census division (Ohio, Indiana, Illinois, Michigan and Wisconsin), the largest of the nine divisional child groups this atlas splits the parent group into. It spans Chicago-centered granger and trunk lines (the Chicago, Rock Island and Pacific Railroad, the Chicago Great Western Railway), Michigan lines (the Michigan Central Railroad, the Ann Arbor Railroad, the Grand Rapids and Indiana Railroad, the Adrian and Blissfield Rail Road), the Baltimore and Ohio Railroad's own Ohio and Indiana mileage alongside its actual Maryland headquarters placed in the South Atlantic group, the Cincinnati, Indianapolis and Western Railroad, and the Duluth, Winnipeg and Pacific Railway. At 75 members it sits under this atlas's oversized-group threshold and needs no further split at this time.