Ohio State set as largest favorite in modern series history against Michigan, with a 23.5-point spread ahead of their regular season finale. This is the largest difference since 1978, despite recent history favoring the Wolverines with a three-game winning streak.

Source: https://www.cbssports.com/college-football/news/ohio-state-vs-michigan-odds-buckeyes-set-as-largest-favorite-over-wolverines-in-modern-series-history/