Lines are grouped into historic operating divisions. As passenger service declined during the 1950's, many divisions were consolidated.
Illinois Central historically identified its lines as districts, prior to adopting the CN term subdivision.
Main Line (Chicago-Richton)
South Chicago Branch/Blue Island Branch
Broadview District (Chicago-Broadview)
Chicago District (Richton-Champaign)
Gilman Line (Gilman-Springfield)
Champaign District (Champaign-Centralia)
Effingham District/Indianapolis District (Effingham-Indianapolis)
Springfield District (Springfield-East St. Louis)
Clinton District (Centralia-Clinton)
Amboy District (Clinton-Freeport)
Peoria District (Peoria-Mattoon)
Mattoon District (Mattoon-Evansville)
Havana District (Champaign-Havana/Decatur)
Centralia District (Centralia-Cairo)
St. Louis District (East St. Louis-Du Quoin)
Murphysboro District (Pinckneyville-Carbondale/Mounds)
Freeport District (Broadview-Freeport)
Dubuque District (Freeport-Dubuque)