If you want to know how Donald Trump became president—and whether it can happen again—you have to look to Wisconsin. A travelogue.

Before November 8, 2016, Wisconsin was viewed by many as part of a “Blue Wall” of Midwestern states that would form the backbone of a Democratic win in that year’s presidential elections. Afterall, the state has a long progressive history and had not voted for a Republican presidential candidate since 1984. That is why the shock was so deep when Donald Trump was able to eke out a victory there, which together with surprise wins in Michigan and Pennsylvania delivered the presidency to him.

In many ways, Wisconsin, yet again a battleground state in 2020, highlights the key dividing lines which contribute to American political polarization—the key driving force in U.S. politics today. A trip through the state thus allows us a look at the racial, cultural, and economic divisions that are visible in the country writ large. The coronavirus has made this year’s presidential election more unpredictable. So far, Joe Biden is leading in most of the polls in Wisconsin, but after the 2016 experience, their significance for many observers has declined. Perhaps by the end of 2020, journalists will again travel to places like Prairie du Chien or Milwaukee to investigate how Wisconsin decided the election.