The Flint Subdivision is a railway line in the state of Michigan. It is owned by the Canadian National Railway and runs from a junction with the Michigan Line and CN's South Bend Subdivision in Battle Creek, Michigan, to Port Huron, Michigan. At Port Huron, on the shores on Lake Huron, it connects with the Strathroy Subdivision which runs through the St. Clair Tunnel into Ontario. Historically, the line was part of the Grand Trunk Western Railroad mainline between Chicago and Toronto.

Flint Subdivision
Overview
Owner	Canadian National Railway
Locale	Michigan
Termini	Battle Creek, Michigan Port Huron, Michigan
Service
Services	Blue Water
Technical
Line length	158.7 mi (255.4 km)
Number of tracks	1
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Route map Legend CN to London Canada United States St. Clair Tunnel 61.7 mi 334.2 mi Port Huron CSX to St. Clair Tunnel Yard CN to Detroit 290.0 mi Lapeer CSX 270.0 mi Flint Torrey Yard HE to Owosso 253.3 mi Durand CN to Detroit 223.9 mi East Lansing CSX to Detroit CSX to Grand Rapids NS to Jackson Battle Creek Yard Amtrak to Detroit 175.8 mi Battle Creek Amtrak to Porter CN to Munster [1] This diagram: view talk edit

Today the line mostly handles freight. Amtrak's Blue Water uses the line between Battle Creek and Port Huron.