A month before the 2016 presidential election, few serious analysts believed that Donald Trump could possibly win. A week or even a day before the election, this consensus had not changed. The certainty of these analysts lay in the "Blue Wall" of states that had voted consistently Democratic in presidential races for more than two decades. Trump would have to breach the Blue Wall, they all agreed, to have any chance of success.
On Nov. 8 Trump carried every Rust Belt state from Iowa to Pennsylvania, except Barack Obama's home state of Illinois. Three of these -- Pennsylvania, Wisconsin, and Michigan -- were critical and had not gone Republican in 24 years. Trump won six states that Republican Mitt Romney failed to carry four years earlier.