The lesson is that voters in both parties are in a very anti-establishment, populist mood. Hillary Clinton is the establishment candidate.

Senate races have tightened along with the presidential race. Watch to see how many Republican Senate candidates outperform Donald Trump - and how many hang on to their seats in states that he loses.

The winner's margin of victory also matters. If it's a squeaker, that will make the lessons learned for both parties much murkier.

If [Hillary] Clinton can come close in those two traditionally red states, it will be because of the diverse, educated populations around Atlanta and Phoenix. And it will be a sign that Arizona and Georgia are on their way to becoming the new battleground states.

Donald Trump is a candidate who divided his own party more deeply than any presidential candidate has before.

If [Donald] Trump wins narrowly, Democrats can blame the loss on FBI director James Comey, who inserted himself late in the campaign in an unprecedented way.

[Donald] Trump's path to victory depends on getting historic levels of support from white voters, and particularly large numbers of white, non-college-educated voters.