https://www.nytimes.com/2019/03/11/us/politics/dnc-milwaukee-2020.html?
Before 2016, the last time a Democrat lost Wisconsin in a presidential election was 1984 when Reagan swept 49 states. Wisconsin was VEERRRYYYY close in 2000 and 2004, however, with Democrats winning by 0.22% in 2000 and 0.38% in 2004 (the closest of all swing states that year).