But that's not what exit polling shows in those states, to Southpaw's point. Exit polls show Hillary Clinton winning a majority of the vote from people who told pollsters that the economy was the most important issue facing the country. What's more, in each state, a majority of voters said that was the case.
In fact, if we extend that out to every state for which we have exit polling, in 22 of those 27 states a majority of people said that the economy was the most important issue. And in 20 of those states, voters who said so preferred Hillary Clinton. In 17, in fact, a majority of those voters backed Clinton.
The circles with bright red slices are those in which voters who thought the economy was the most important issue either preferred Trump or preferred both candidates equally. Those are all states that went for Trump. In every other state, voters most worried about the economy preferred Clinton, even though she lost eight of those states.
In nearly every state, Clinton did better (and Trump worse) with voters worried about the economy than with the overall pool of voters. (Notice how the blue slices in the smaller circles extend further than the blue slices in the larger ones.)
How can that be? How can she win a majority of the majority and still lose? Because she lost with other groups worse.
The exit poll questionnaire gave voters a choice between four options for the most important issue. Clinton was generally preferred by those who said foreign policy was the most important issue, too, but Trump was preferred by those who saw immigration or terrorism as most important. The key is the margins. On average, about 13 percent of people in the 27 states said foreign policy was most important and they preferred Clinton by an average of 30 points. On average, voters who said the economy was most important preferred Clinton by 7.3. But on terrorism, rated most important by a fifth of voters, on average, Trump led by an average of 21.8 points. On immigration (most important to an average of 12.2 percent of respondents)? A huge 42.1 percentage point lead for Trump.
Trump's narrow wins in those three key states mean that any number of factors could have been the determining one. But across the country, the story told by the exit polls seems clear: Trump didn't win because people were worried about the economy. He won thanks to people who were worried about the subjects of immigration and terrorism that he started hammering on from the very first day of his campaign.