Lines are grouped into historic operating divisions. As passenger service declined during the 1950's, many divisions were consolidated.
3rd District (Detroit-Montpelier)
1st District (Montpelier-Peru IN)
2nd District (Peru IN-Danville)
4th District (Gary-Montpelier)
6th District (Chicago-Forrest)
7th District (Forrest-Bement)
9th District (Danville-Decatur)
10th District (Decatur-Hannibal)
13th District (Decatur-East St. Louis)