The Sault Sainte Marie International Bridge (or as International Bridge) spans the St. Marys River and is a United States/Canada international border crossing. Also is the north terminus of Interstate 75.
Check out the annual International Bridge Walk every June!
Have your passport ready.
Try not to cross at peak times. I crossed at about 10:30 am on a Saturday and only had to wait about 10 minutes
Bring a book to read while you wait.