The polls are tightening and both candidate are gunning each other with seldom seen violence. And the candidates sometime incite violence themselves.
While the polls are really tight, the electoral college is quite firmly in the hand of Clinton (287 vs 174 today, with 270 needed to win). Electors, in most states, are not required to follow the popular mandate.
We could have easily a situation like Bush Jr. vs Al Gore, where the headcount vote went to Gore, but the electoral college voted Bush Jr.
We would have been much better with Al Gore I presume – probably without Iraq descending into chaos and the rise of Islamic State.
The issue is the Trump will not go resign to the rules as Al Gore did, so there is the real prospect of Court challenges and real violence – specially with the number of guns in the USA.