Everyone knows that rural America has gone deep red. That trend came last to the Upper Midwest, but it has arrived in Minnesota with a vengeance. Minnesota’s 8th Congressional District, home to the state’s mining industry, is heavily unionized and was long a Democratic Party bastion. No longer: the 8th, along with the rest of Greater Minnesota, is now Trump country. It is represented by Republican Pete Stauber, a former police officer and union member, who has been endorsed for re-election by every private sector union. Today it would take a miracle for a Democrat to win that seat. In...