From what I can see, the leaves are 'odd pinnate' and opposite along the branch. It seems to be a type of Ash, there's only four listed in Minnesota.
http://luirig.altervista.org/f...
Of the four, Fraxinus pennsylvanica looks most likely but some of the leaves on your tree are unequally lobed at the base. Some are equal, so maybe this is something peculiar to this species.
I found a photo of leaves which look unequally lobed at the based, but your leaves look to be more serrated.
https://www.google.co.uk/searc...
The only other genus listed in the same family Oleracea in Mn is Syringa.
This site also suggests an Ash.
http://forestry.about.com/od/t...
