Did you call MADDAC, to see if he was picked up. Or the Milwaukee Humane Society, local vet clinics. Post color pc flyers in the local gas stations, stores. I'd even call the schools in your area and post office. To ask if they've seen him. Or might spot him in a house window sleeping or crying. Ask neighbors to check under their porches, any dog houses or sheds in their yards too. I hope he's found safe and returned soon.
Hope u find your kitty❤️
Place his dirty litter box outside your house in a covered area until he returns. Cats can smell their litterbox up to 1 mile away and find their way back home.
Put food near your door. Place a baby monitor and/or home security camera near the food so you can hear/see when your cat is there eating and go and get him/her.
Check MADACC and other humane societies. Post on Lost Cats of Wisconsin.
Check under bushes and other places in your yard and neighborhood to see if he is hiding there. Cats become scared and won't come when called.
Don't give up. People find their cats months later. Prayers!
Also recheck the house???