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)
New Castle Subdivision (Willard-New Castle)
Newton Falls Subdivision (Ohio Junction-Newton Falls)
Line Sold to Wheeling & Lake Erie Railway (New Company)
CT&V Subdivision (Valley Jct.-Witco-Sandy-Canton)
Line Sold to Akron Barberton Cluster Railway
CT&V Subdivision (Canton-Akron)
Line Sold to Cuyahoga Valley Scenic Railroad
CT&V Subdivision (Akron-Cleveland)
Abandoned Lines
Lake Subdivision (Deforest Junction-Fairport)
Newburg Subdivision (Willow-Newburg)
Wooster Subdivision (Lodi-Wooster)
Indiana Subdivision (Cincinnati-Washington IN)
Illinois Subdivision (Washington IN-East St. Louis)
Louisville Subdivision/Jeffersonville 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
Decatur Subdivision (Indianapolis-Hillsdale IN-Decatur IL-Springfield)
Abandoned Lines
Brazil Branch (West Melcher-Brazil)
Toledo Subdivision (Cincinnati-Toledo)
Middletown Subdivision (New River-Middletown)
Abandoned Lines
Wellston Subdivision (Dayton-Wellston)
Bowling Green Subdivision/Findlay Subdivision
Dayton & Union Subdivision/P&T Subdivision
Lines Sold to Columbus & Ohio River Rail Road
Central Ohio Subdivision (Bellaire-Cambridge-Newark)
Columbus & Newark Subdivision (Newark-Columbus)
Lake Erie Subdivision (Newark-Mt. Vernon-Mansfield)
Lines Sold to Ashland Railway
Lake Erie Subdivision (Mansfield-Willard-Sandusky)
Lines Sold to Indiana & Ohio Railroad
Midland Subdivision (Midland City-Columbus)
Abandoned Lines
O&LK Subdivision (Zanesville-Belpre)
Shawnee Subdivision/Eastern Ohio Subdivision
Lines Sold to Indiana & Ohio Railroad
Chillicothe Subdivision (Cincinnati-Midland City)
Chillicothe Subdivision (Midland City-Greenfield-Chillicothe)
Lines Sold to Great Miami & Scioto Railway
Parkersburg Subdivision (Chillicothe-Red Diamond-Parkersburg)
Portsmouth Subdivision (Hamden-Fire Brick-Portsmouth)
Abandoned Lines
Hillsboro Subdivision (Blanchester-Hillsboro)
CL&W Subdivision/Cleveland Subdivision
Line Sold to RJ Corman Lines)
CL&W Subdivision (Bellaire-Uhrichsville-Warwick)
Line Sold to Wheeling & Lake Erie Railway (New Company)
River Subdivision (Terminal Jct.-Benwood)
via Metra (Chicago-Joliet)
New Rock Subdivision (Joliet-Utica)