Most importantly, they indicated their views on three key issues: trade, immigration, and the United States' relationship with China. They were specifically asked whether the U.S. should have more or fewer trade agreements with other nations; whether a pathway to U.S. citizenship should be offered to undocumented immigrants; and whether China's emergence as a rival superpower is more an opportunity or a threat.
Mutz found that, in 2012, "the two parties candidate positions on trade, as well as the average American's position, were all but indistinguishable." However, by 2016, a large gap opened between the pro-trade views of Democratic candidate Hillary Clinton and the largely anti-trade views of Trump, whose attitude was much closer to that of the average American.
Similarly, views on immigration and China became polarized, with Trump asserting positions that were far closer to those of the average American. Voters noticed this, and many voted accordingly.
"Voters who shifted (parties) to become Trump voters between the two elections seem to have done so because of increasing distance between their own views and that of the Democratic candidate on trade, immigration, and China," Mutz reports