In Chicago, Kindra, Cal River Fleeting, Illinois marine Towing is A little South of Chicago.
Selvick towing in Sturgeon Bay
Tug Manitou in Port Huron
In Detroit there is Gaelic Towing.
Andrie is all lake tugs and based in Muskegon.
There are also a few construction and dredging companies. Ryba, Luedke, Deroche(spelling?)
Port City Towing in Muskegon
Dann Towing has a couple of boats on the Lakes in the Summer, one is operating out of Detroit.
Only the Chicago boats are push boats, generally speaking.