I am not sure what trees grow in that area, but I believe you would have birch growing in that area. According to The Bowyer's Bible One, you can make good bows as long as they are wide. I think you may find American Elm and Burr Oak or Red Oak in that area as well if you are lucky. Most any hard white wood should make a bow. I also think you may find some buckthorn growing in that area. I haven't used it, but have heard it makes a good bows. Ironwood (Hophornbeam) is supposed to grow throughout Minnesota and is good bow wood. I don't know if this helped you or not.
If you have trouble finding suitable wood, then PM me. I live in Southeast Minnesota and have access to a lot of good bow woods. If you ever get in this area I could give you a stave. I currently have staves of hophornbeam, white ash, slippery elm, shagbark hickory, bitternut hickory, and hackberry. I can get other wood as well.
Swampman