Like Mullet said, I too have heard that there is no actual flint in the US, just variations of low to high quality chert. I once mentioned that to a man from Ohio, who was showing me a piece of horn stone, and he proceeded to tell me all about "Flint Ridge" in Ohio! He was very adamant about there being "Flint" there!If you want to split hairs, what is Flint? Very high quality Chert? Or another amalgam of silicates? If you are trying to get a spark from the rock in your area, be sure to use carbon steel, not stainless.
Just do like they said knock off a corner, and see how it reacts, and if it looks glassy, or slick. I don't know if Wisconsin has "flint" or chert, or not. I did find an arrow head on my uncle's dairy farm, where the cows walked to the barn. I don't know if it was local rock, or trade material. Good luck.
Wayne