All signs point to a Clinton win (but…)
Hillary Clinton's big advantage in national polls eroded after the FBI intervention 11 days before the election. But even before Sunday's announcement that the investigation into her e-mail practices won't be reopened, her lead seemed to have stabilized at a narrower margin.
Because more electoral-college votes are safely Democratic to begin with, Ms. Clinton has a much easier path to victory than Donald Trump – needing to lock up only a few battleground states, where she is mostly leading or tied in the polls, whereas the Republican nominee needs to almost run the table.
Very high Hispanic turnout in early voting is encouraging for the Democrats in states such as Nevada and Florida, the latter of which Mr. Trump absolutely can't afford to lose. And Ms. Clinton generally has the vastly superior get-out-the-vote operation.
One caveat, at the end of a very strange and unpredictable campaign, is that campaigns' internal tracking is always more sophisticated than public polls – and Ms. Clinton didn't end the campaign acting like someone with a really big lead, turning up in states such as Michigan and Pennsylvania that Democrats haven't lost in ages. She may just be playing it safe, but it's enough to keep others a bit on edge.
The senate is there for the Democrats' taking
The Democrats are unlikely to be satisfied with a win by their presidential nominee alone, because Mr. Trump's unpopularity gives them a very good chance of also winning back control of the Senate, which they lost in 2014.
Only four seats would have to switch from the Republicans to the Democrats for majority control to flip. Knocking off incumbent Mark Kirk in Illinois is widely expected to get them a quarter of the way there, and Wisconsin's Ron Johnson also seems likely to go down. That would leave the GOP needing to hang on to all but one of the seats up for grabs in closely contested races in North Carolina, New Hampshire, Pennsylvania, Missouri and Indiana. (The Republicans' lone hope for a pickup, the Nevada seat being vacated by retiring Senate Democratic Leader Harry Reid, now looks very faint.)
Even if the presidential race is decided early, the Senate battles should make for some drama through the evening as Ms. Clinton waits to see if she will face less gridlock than Barack Obama has had to contend with the last two years – or a lot of second-guessing about how she didn't manage to help with down-ballot victories.
The House of Representatives should stay Republican
Nobody should get too excited about that gridlock easing up, because there's been plenty of it ever since the Republicans took control of the House of Representatives in 2010 – and the GOP's chances of keeping it are much better than with the Senate.
When Mr. Trump was cratering in October, the Democrats got more optimistic about taking away the 30 Republican House seats needed to give them congressional control.
But most projections now suggest Democratic gains – at a level where gerrymandered districts make things easier for incumbents on both sides – will be limited enough for the Republicans to keep a slim edge, and keep making things difficult for a Democrat in the White House.
Trump's concession (?) speech might really matter
Not many people were breathlessly waiting to see what Mitt Romney, John McCain or John Kerry had to say the nights they went down to defeat. But it will be a different story if Mr. Trump loses.
The Republican nominee has pointedly refused to say he will accept the result if it's in Ms. Clinton's favour. He doesn't need to accept it, of course, for it to count. But he has already riled up his supporters by claiming the election is rigged, and the likes of Milwaukee County Sheriff David Clarke – one of Mr. Trump's campaign surrogates – has called it "pitchfork and torches time."
Faced with the chance of violent unrest, even just from a few fringe supporters, most candidates would respond to a decisive defeat by calling for unity. That may be too much to expect from Mr. Trump. But if he turns up the temperature any more, he will be playing with fire.
The path to victory could point to the future
Until recently, Democrats were supposed to have an easier time in states such as Pennsylvania and Michigan than Florida or North Carolina. Now, there is a chance Ms. Clinton will win more comfortably in the southern battlegrounds than the northern ones.
She is also likely to lose Ohio and Iowa, but is in good shape in Nevada and Virginia, and has an outside shot at taking heretofore Republican strongholds such as Arizona and Georgia.
All this is eminently worth watching, even if Ms. Clinton wins by a large enough margin for individual battlegrounds not to be decisive, because it points to the impact of shifting demographics: southern and southwestern states becoming younger, more educated and more diverse as the Rust Belt gets older and whiter.
Mr. Trump's nativist candidacy, which has brought more working-class whites into the Republican fold while repelling others, has accelerated the political impact of that shift.
But once a party captures a state once, it's easier to win there in future. So what happens on Tuesday could help reshape the electoral map – and the imperatives for both parties – for elections to come.