For the first time since 2010, Democrats will lead the House of Representatives when the 116th Congress convenes early next year — while Senate Republicans will have padded their 51-seat majority by a few more, leaving them far below a filibuster-proof margin of 60 votes.

What does it all mean? Here are four takeaways from Tuesday night’s results.

1. It’s not always the economy, stupid

Midterm elections offer voters a chance to hold the president’s party accountable — typically for the state of the economy under the president’s watch. But with a strong economy and unemployment at its lowest in nearly a half-century, these elections were a referendum on Trump’s presidency. The results display a deeply divided electorate. City and suburban dwellers rejected the president’s inflammatory behavior and xenophobic policies; rural voters embraced him.

The result is a split-screen Congress. Democrats registered their opposition with record turnout in blue and purple districts, electing a record number of women, including several women of color, to take control away from Republicans for the first time in eight years. Across the Hill, Trump notched a major win by expanding his majority in the Senate by at least a couple of seats.

2. Democrats will investigate more than legislate

Voters have handed Democrats significant power to investigate any alleged wrongdoing by Trump and his administration. Democrats can thank Republicans for changing House rules in 2015; now most committee chairs can unilaterally issue subpoenas without consulting the minority party.

Democrats will surely use this unfettered authority to investigate Trump’s family businesses, ethics charges against several of his Cabinet members, and Trump policies such as the Muslim travel ban and separating migrant families at the border. Depending on the course of the Mueller investigation, the House Intelligence Committee is likely to toughen its oversight of the Trump campaign’s conduct in the 2016 elections.

3. A more polarized Congress as the GOP moves further right and the Democrats further left

The elections have deepened the divide between the parties.

Both House and Senate Republican conferences will look a lot Trumpier in the new Congress.

In the Senate, Trump will rightfully claim credit for bolstering GOP numbers. Since Trump all but put himself on the ballot, we should not expect to see much daylight between him and the new GOP senators. With a wider margin and more conservative conference, centrists Susan Collins of Maine and Lisa Murkowski of Alaska lose their pivotal status; on most issues, Republicans will not need their votes to make a majority.

In the House, Republicans primarily lost seats in purple suburban districts, many of which had voted for Hillary Clinton in 2016. That leaves the smaller GOP conference redder and closer to the president. But it still has some moderates — which means, now that Speaker Paul D. Ryan (Wis.) is retiring, the GOP’s leadership contests may be even more complicated.

Senate Democrats, meanwhile, move left. Losing red-state Democratic colleagues means Democratic leader Sen. Charles E. Schumer (N.Y.) will not have to accommodate as broad a mix of electoral interests. Expect Democrats to stick together to oppose Trump’s nominees and GOP proposals more uniformly.

On the House side, the new Democratic speaker — maybe Nancy Pelosi (Calif.) — faces a tougher leadership challenge. Just as we saw when Democrats regained control of the House in 2006 and lost it in 2010, the new Democratic majority is built on Republican turf. A decade ago, Pelosi called these members her “majority makers.” Similarly, the next Democratic speaker will, on the one hand, need to meet the demands of the party’s base not to cooperate with the president — while, on the other, ensuring new members from purple districts can satisfy their own constituents. Finding issues and bills that unite a broad array of Democrats will be the key challenge for Democratic leaders.

4. Gridlock anyone?

Stalemate is common when parties split control of Congress. Indeed, as shown in the figure below, split-party congresses (1981-1986, 2001-2002, 2011-2013) face legislative stalemate more frequently on salient issues than do congresses with unified or completely divided control.

So will the two parties make deals to pass laws? That seems, shall we say, unlikely, given the increasingly polarized parties and an approaching presidential election. Trump seems unlikely to move to the center to push for new investments in infrastructure or a resolution on immigration. Democrats could be wary about cutting taxes on the middle class without raising them on the wealthy, and a Democratic House will oppose limiting entitlement spending. Nor is a split-party Congress likely to agree to a congressional budget. That means Republicans will not be able to keep resorting to reconciliation bills — which cannot be filibustered — to advance measures with a simple majority.

That said, Congress will have to make at least some deals. The government is expected to hit its debt ceiling in early March. And a new spending deal will be needed to lift tough budget caps on domestic and defense spending come fall 2019. How Trump and Congress decide to exploit these must-pass bills remains to be seen, but the sausage-making is unlikely to look or smell very good.