Wisconsin's ghost towns are not Western mining camps, and most of them have left little to see. The oldest come from the lead rush in the southwest: by 1829 the district had 4,253 miners and 52 licensed smelters, and in the 1840s it produced more than half the nation's lead before the strikes played out and the California gold rush pulled men away. Belmont, the territory's first capital in 1836, and the river port of Sinnipee belong to that era. Farther north, the pine lumber boom built mill towns and railroad sidings that emptied once the timber was gone. On October 8, 1871, the night the Peshtigo fire killed an estimated 1,200 to 2,500 people, fire also wiped out Williamsonville in Door County. Quarry company towns like Stonehaven, Black farming settlements like Pleasant Ridge and Cheyenne Valley, Norwegian and Swedish colonies like Muskego and New Upsala, and river towns flooded by dams, Quincy under Castle Rock Lake and, by Wikipedia's account, Sinnipee in 1934, fill out the list.
Expect cemeteries, markers, foundations and a few restored buildings rather than streets of empty storefronts. The best stops are public: the two restored 1836 buildings at First Capitol near Belmont, the quarry lake and foundations of Stonehaven in Harrington Beach State Park, the well at Tornado Memorial County Park, and the well-kept 1840s village of Cooksville, which never emptied.