Update: None of these four scenarios has come to pass, after Donald Trump was just named the winner of Pennsylvania -- and likely soon the presidency. But we got surprisingly close. The original post follows.

The below is unlikely to happen. But it's significantly more plausible than it once seemed.

The 2016 election could end in a 269-269 tie, sending the race to the (GOP-controlled) House to decide who the next president is.

Here's Scenario No. 1, in which Donald Trump pulls the upset in Wisconsin, while Hillary Clinton carries Michigan, Pennsylvania, New Hampshire and Nevada.

And here's Scenario No. 2, in which Trump loses Michigan, Pennsylvania and Wisconsin but carries Nevada and New Hampshire.

Update: The below maps are off the board, with Trump being declared the winner of Utah.

And Scenario No. 3 in which this goes to the House would be if Trump wins Michigan, loses Pennsylvania, Wisconsin, Nevada and New Hampshire, but also loses Utah to independent Evan McMullin -- who has polled tight with Trump -- or to Clinton. Either way, Trump would be at 269 electoral votes; Clinton would be at 263 if McMullin won Utah or 269 if she won it.

And Scenario No. 4, which is No. 1, but with Utah going blue and Nevada going red:

A big x-factor in all of this -- and something that frankly makes this speculative exercise difficult -- are the two states that award electoral votes by congressional district. It looks very possible Trump could win one in Maine's more rural 2nd district; he currently leads there by double digits with 70 percent of precincts reporting, according to the Portland Press-Herald. The Clinton campaign, meanwhile, hopes to steal one in Nebraska's Omaha-based 2nd district, which President Obama won once and where she currently trails by 3 points. Moving either of those votes could give either candidate 270. The more likely would seem to be Trump getting No. 270 in Maine. (And moving both would keep each at 269.)

But even then, you have the issue of faithless electors. At least one Democratic elector in Washington state says he won't vote for Clinton, and another is threatening to. Some Republican electors have suggested they might spurn Trump too, but quickly backed down. If the electoral college is that close, these faithless electors come into play.

If it does go to the House, here's what happens in that scenario, according to the National Constitution Center:

In a tie scenario, the election would eventually head to the House of Representatives and the Senate, under the 12th Amendment, assuming that the final Electoral College vote is similar on December 19, 2016.
This has happened twice before. After the 1824 election, when no presidential candidate won a majority of the electoral votes, the House picked John Quincy Adams over Andrew Jackson (who had the most popular votes) as President. And after the 1836 election, there was a contingent election in the Senate for Vice President won by Richard Mentor Johnson.
Before the contingent elections get to the House and Senate for a vote, however, several things need to happen. First, at a state level, the election results need to be confirmed; in particular, the winning slate of electors for a state is confirmed. This is where the disputes in 1876 and 2000 over electors had to be resolved.
There are also the possibilities of recounts and contested elections within states where a recount is automatically triggered (like the 2000 contest in Florida) or of a legal action leading state courts to decide lawsuits related to contested elections.
Under a federal law known as the safe-harbor provision, a state must determine its electors six days before the Electoral College members meet in person. In 2016, that safe-harbor deadline is December 13, since the college votes on December 19.
The electors for each state convene on December 19, 2016, at their state capitols and in the District of Columbia. In 48 of 50 states, just the electors who represent the candidate with the most popular votes on Election Day each get to cast votes in the Electoral College election. (Maine and Nebraska split votes by congressional district.) Each state group sends its endorsed, official vote count certificate to the Vice President (acting as President of the Senate), state officials, the federal court that had jurisdiction over the state capital area, and the federal Archivist. The vote certificates must be received in Washington by December 28.
In 2017, the new federal Congress convenes on January 6 for the official Electoral College vote count. The Vice President will open the vote certificates and pass them to four members of Congress, who count the votes. If there is a majority winner with at least 270 electoral votes and there are no objections filed by members of Congress, the Presidential election is certified and over. If there isn’t a majority winner, the House decides who is President; the Senate decides who is Vice President.
In the House, each state delegation gets one vote in the presidential contingent election. Currently, the Republicans have the clear majority in 33 state delegations out of 50 in the House, before Election Day. Each member of the Senate gets one vote in a contingent election. That could allow for the unlikely pairing of a President and Vice President from different political parties – which hasn’t happened since 1796.
And there are also some unlikely but possible scenarios. For example, there could be a vote cast by a faithless elector at the state level during the December 19 electoral college vote, which may lead someone in the House or Senate to contest that vote.