In social science we recognize that there is more than one reason that explains social phenomena. It is the one good impulse behind the complicated models we use in academic writing to try to prove a particular hypothesis, but leaves most people out of the conversation. This is a frequent complaint we hear that our journals are too mathematically oriented and don't address real world concerns. But like with many bad ideas, there is more than a grain of truth in the premise. There is no direct cause and effect that makes one thing the true answer. It is many things.
So why did Hillary Clinton lose Wisconsin to Donald Trump (by a skinny 27,000 votes)? There are most likely many reasons. First and foremost, the decline in voter turnout. As of today the total vote cast in Wisconsin is down 120,000 votes from 2012. Based on Dave Wasserman's vote count total (which seems very comprehensive) and state archives, that decline is almost all explained by the reduction in the Clinton vote from where Barack Obama stood in 2012. Obama 1.62 Million in 2012 and Clinton 1.382 Million while the Romney to Trump vote was down only 5000.
In Milwaukee county alone the turnout was down 52,000 votes from 2012 and there is a great explanation of most all of Clinton's loss of 27,000 statewide. However, in Dane County (home to Madison) the vote total was about the same as in 2012 and Clinton actually performed a small amount better than Obama (2000 votes) and overall turnout was up 6000 plus. Clinton also did a small amount better than Obama in suburban Waukesha County (where she and other democrats do poorly but still) while Trump was down 20,000 votes from Romney's total four years earlier. In fact, across the three counties Clinton's margin increased over Obama's by 20,000 (245,811 from 225,425).
So the rest of the state must have been a disaster. And it was. Compare the 2012 map with the 2016 map and you can easily see the wave of red that took over other counties in the state. So the question is still why? The mix of answers that we have seen across the flipped states probably apply ... voter suppression (a form of racism), the impulse for change, poor campaign messaging and tactics (for the region), the email nonsense, sexism and general lack of enthusiasm for the candidates. In order to address these issues the Democratic Party should take the time in 2017 to go talk to voters in the flipped counties and get a sense for what is on their minds. This is critical to mount a comeback at the state and local level in 2018.