One good thing about setting up these sites is you find things you may have missed.
It turns out I’ve never found Johann in the 1870 Census. I did another go-around and I still haven’t found him. He is listed in the 1860 Census at the age of sixteen living with his parents. He is listed in the 1880 Census at the age of 35 living with his parents, again. His parents are listed in the 1870 Census with some of their children, but John is not there. I thought maybe he was doing something related to the Civil War, since he was about the right age, but no luck there. I’ve looked through the Grafton census page-by-page, but I did not see him. I’ve also done some searching on the Port Washington, Cedarburg, and Mequon census records, which are nearby. I wonder where John was in 1870.