1. Democrats took control of the House of Representatives and elected Nancy Pelosi as speaker, returning divided government to Washington.

The power shift came amid a partial government shutdown, with President Trump’s insistence on a wall on the Mexican border running headlong into newly energized Democratic opposition. House Democrats are voting on two new bills to reopen the federal government this evening, but their prospects in the Senate seemed dim.

Hours before her election, Ms. Pelosi, center, suggested in an interview that a sitting president could be indicted and left open the option of impeachment, kicking off what could shape up to be a memorable term.