Lines are grouped into historic operating divisions. As passenger service declined during the 1950's, many divisions were consolidated.
Milwaukee Road and Soo Line historically had numbered subdivisions, which were renumbered over the years as operating divisions were consolidated. Named subdivisions were adopted after Soo Line acquired the Milwaukee Road, and are used here. Certain lines abandoned longer ago are identified differently.
First Subdivision (Chicago-Elgin)
Second Subdivision (Elgin-Savanna)
Fourth Subdivision (Savanna-Moline)
First Subdivision (Chicago-Rondout)
First Subdivision (Rondout-Milwaukee)
Second Subdivision (Rondout-Janesville)
First Subdivision (Milwaukee-Green Bay)
Second Subdivision (Green Bay-Channing)
First Subdivision (Milwaukee-Portage)
Second Subdivision (Portage-La Crosse)
M&P Subdivision (Madison-Portage)
Valley Subdivision (New Lisbon-Woodruff)
Janesville Subdivision (Davis Jct.-Janesville)
Racine & Southwestern Line (Racine-Beloit)
Racine & Southwestern Line (Beloit-Kittredge)
Madison Subdivision (Janesville-Madison)
Prairie Subdivision (Madison-Prairie Du Chien-Marquette)
Waukesha Subdivision (Brookfield-Madison)
Terre Haute Division (Chicago-Terre Haute)
Terre Haute Division (Terre Haute-Westport)
Sullivan Branch (Blackhawk-Sullivan)
Evanston Division (Chicago-Wilmette)