The west branch begins directly southwest of the city of Swartz Creek in Gaines Township. It then flows northeast through the city and then through Flint Township, where it meets the eastern branch at Bristol Road and I-69.
The western limb begins immediately south-southwest of Swartz Creek in Gaines Township. It then moves north-east through the city and enters Flint Township, where it converges with the eastern limb at Bristol Road and I-69.