Baltimore & Ohio adopted named subdivisions for its lines at least a hundred years ago.
Altenheim Subdivision (Chicago-Forest Park)
Blue Island Subdivision (Chicago-Blue Island)
Barr Subdivision (Blue Island-Pine Jct.)
Lake Subdivision (South Chicago-Pine Jct.)
Chicago Heights Subdivision (Blue Island-Chicago Heights)
Garrett Subdivision (Pine Jct.-Garrett)
Willard Subdivision (Garrett-Willard)
Indiana Subdivision (Cincinnati-Washington IN)
Illinois Subdivision (Washington IN-East St. Louis)
Louisville Subdivision (North Vernon-Charlestown-Louisville)
Abandoned Lines
Springfield Subdivision (Shawneetown-Beardstown)
Earlier Abandoned Lines
Ohio River Division (Olney-Hume-Sidell)
Connected with main line at Olney.
Indianapolis Subdivision (Hamilton OH-Indianapolis)
Sexton Branch (Rushville-Sexton)
Line Sold to Decatur & Eastern Illinois Railroad (Short Line Operator)
Decatur Subdivision (Indianapolis-Hillsdale IN-Decatur IL-Springfield)
Abandoned Lines
Brazil Branch (West Melcher-Brazil)
via Metra (Chicago-Joliet)
New Rock Subdivision (Joliet-Utica)