Democrats won the House in a wave, while Republicans outperformed expectations in the Senate, leaving political observers scrambling to figure out what it all means.
But, as the results came in, some clear implications emerged for the future. Dozens of theories of how to win were tested by both parties. Some worked, some didn't. And the shockingly high turnout offered seeds of hope to both sides that their coalition may be durable for 2020.
Here's what the results tell us so far:
1. The Trump effect is real
There were two broad schools of thought on 2016: Either Donald Trump was a fluke president who only won by drawing an unpopular opponent, the divine intervention of James Comey and a complacent Democratic base — or he was a singular figure who had fundamentally reshaped the electorate.
Tuesday offered a boost to the latter theory, with some positive results for his party amid a whole lot of negative ones.
No one could say voters were caught off guard this time. Turnout soared in comparison to prior midterms. And once again, many of the trends that helped elect Trump, even as he lost the popular vote, held true.
Just like in 2016, rural voters in 2018 turned out in droves to elect Senate candidates in states Trump won, like Indiana, Missouri, North Dakota and even purple Florida.
But, in another echo of 2016, Trump did catastrophic damage to Republicans in the suburbs, long a traditional source of strength for the GOP. From Fairfax, Virginia, to Dallas, Texas, these angry voters made it clear early that Democrats would capture the House, even with a map whose gerrymandered lines strongly favored Republicans.
The wild card for the president is the Rust Belt and Midwest — the "blue wall" that Trump smashed in 2016 — which sent mixed messages on Tuesday night, with Democratic senators winning easily, House challengers picking up key seats and parties splitting governor races. Expect it to be a major battleground moving forward.
2. It’s not the economy, stupid
What may be the most unusual aspect of the midterm cycle is that voters overwhelmingly backed Democrats in the House even with unemployment low and wages growing.
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In exit polls, 41 percent of voters cited health care as the most important issue, which Democrats universally emphasized in races, while 23 percent named immigration, which Trump focused on in the final weeks. Just 21 percent named the economy, the only time in at least a decade that it hasn't topped the list, and a significant 11 percent named gun policies. Two-thirds said the president was important to their vote, either to show their support or opposition.
Prior waves have usually been easy to explain. Either the economy was performing poorly (2010), a major war was going badly (2006), or the White House was laid low by scandal (1974). Trump has seen enough scandals for several presidents, but they played a surprisingly minimal role in Democratic campaigns.
That suggests other messages matter a lot more for each party, but it also raises a troubling question for Republicans: If they lose the House by a wide margin when the economy is humming, what happens if things hit a speed bump?
3. The blueprint for Democrats is ... ¯\_(ツ)_/¯
Democrats were hoping Tuesday's results would help them chart a course for the 2020 presidential race by clearly demonstrating that either mobilization (boosting turnout among liberals, minorities and other base Democratic voters) or persuasion (tacking to the center to try to win undecided voters) is the winning strategy in Trump's America.
But instead of a clear signal, they got noise, with conflicting data that is sure to be cherry-picked by both wings of the party to argue the superiority of their side.
On one hand, some of the highest-profile progressive candidates in the country — like Randy "Ironstache" Bryce running for Speaker Paul Ryan's empty seat, Beto O'Rouke in Texas and Kara Eastman in Nebraska — went down to defeat.
On the other hand, so did some of the highest-profile moderate candidates. Sen. Joe Donnelly, D-Ind., who cut TV ads attacking "the radical left,” got crushed, losing by about 9 points. That's the same margin that Sen. Claire McCaskill, D-Mo., is on track to lose by. O'Rouke actually came closer to winning than either of them, losing by only about 3 percentage points.
Florida offers a neat example of the muddled picture: Gubernatorial candidate Andrew Gillum, who touted support from Bernie Sanders and campaigned on marijuana legalization, finished with an almost identical losing margin to Sen. Bill Nelson, D-Fla., who campaigned as a nice-guy moderate former astronaut.
4. Divided government, get used to it
It's never too early to start thinking about the next election and 2020 will be about more than just the presidential race.
First, there's the Senate. If Democrats had held onto a few more seats this year, even if it wasn't enough to win control of the upper chamber, they would be in a better position to retake the Senate in 2020, when they'll compete in a more favorable set of races. But now, they'll face a much steeper climb.
Then there's redistricting, the once-a-decade process where states redraw the boundaries of legislative and congressional districts, which will happen again following the 2020 census. Republicans have been able to hold the House largely thanks to effective gerrymandering after "Democrats picked a bad night to have a bad night" in 2010, as Democratic National Committee Chairman Tom Perez likes to say.
While full state-level results remain to be seen, and there's another election before the map-drawing process kicks in, Democrats missed opportunities to install friendly governors in key states Tuesday, such as Ohio and Florida, which will now have Republican governors in 2020.
5. Political gravity still exists
Trump has been a consistently unpopular president since almost the moment he took office, but his upset win in 2016 and the failure of state polls to see it coming created the impression that he'd devised a new formula that defied all past political logic.
Sure, things looked bad for his approval ratings, but they sure didn't look great when he was caught on tape boasting about groping women, or when he mocked POWs, or when he made what Speaker Paul Ryan called "the textbook definition of a racist comment" about a Hispanic federal judge. These impressions only hardened when his approval rating, however low, seemed to stay stable no matter what chaos was dominating the news or which former aide was pleading guilty to serious crimes.
All of this led many to throw their arms up with a cry of "nothing matters" and assume so-called experts had nothing to offer on how politics works in 2018.
But polling and conventional wisdom — that Democrats would win the House, but lose the Senate — ended up being spot on. It turned out that a president who enters Election Day with a 44 percent approval rating still suffers major losses, just like presidents with similar ratings had before him.
Democrats lost more Senate seats than many predicted, with Florida being the big surprise, and won some House seats no one saw coming, including shock races in Oklahoma, South Carolina, and Trump-friendly Staten Island.
But in general, the pundits got this one right and Trump now looks more mortal than his opponents had initially believed.