Of the 18 midterms since 1950, there have been just five split decisions, where the House shifted towards one party and the Senate towards the other. And 2018's was the most split of them all.
Why it matters: Now that all of the races have been settled — with the exception of the California 21st district race — we can see how much of an outlier the 2018 midterms were. The split is also a sign of how Democrats dominated the suburban House districts while Republicans won the rural Senate states.
Between the lines: In modern midterm elections, the trend has been for seats in both the House and Senate to shift in one direction, usually against the president's party.
The strength of this year's blue wave depends upon how you measure it:
The bottom line: The split decision was no surprise, since the Senate map was historically bad for Democrats. That's why Republicans were able to survive and even improve their numbers a bit in the Senate. But it doesn't mean the wave wasn't there.
Go deeper:
Most of 2018's midterm winners spent more money than their opponents. But some, like Texas senator Ted Cruz and incoming freshman congresswoman Alexandria Ocasio-Cortez, pulled out victories despite being outspent.
Why it matters: Candidates who outspend their opponents usually win. But some political obstacles are so large, even money can't overcome them.
In the Texas Senate race, Democratic challenger Beto O'Rourke, propelled by record fundraising for a congressional candidate, reported net expenditures of $55 million as of the final pre-election filing deadline — about twice as much as Cruz reported spending.
In Missouri, incumbency and a 4 to 1 spending advantage were not enough to save outgoing senator Claire McCaskill.
While most of the outspent winners were Republicans — a side effect of Democrats' significant fundraising advantage — 11 Democrats managed to win their races while spending less than their opponents.
Go deeper:
The tightest midterms races have attracted the most money, according to an Axios analysis of campaign finance filings.
The big picture: As the chart above shows, closer races have attracted the most donor money this election cycle. That's not too surprising, but even non-competitive races attracted a lot of money. In races where the outcome was assured, incumbent favorites crushed their opponents in fundraising.
By the time it's over, the 2018 midterms will have smashed the previous midterm spending record, with candidates spending a combined $5.2 billion, according to a projection by the Center for Responsive Politics. The previous record for midterm spending was about $4.2 billion in 2010, adjusted for inflation.
By the numbers: Texas Senate hopeful Beto O'Rourke, who's trying to unseat Republican incumbent Ted Cruz in one of the most closely watched races in the country, raised more money than any other midterm congressional candidate.
The Cruz-O'Rourke contest exemplifies the trend, but they were not alone: six of the top 10 fundraisers were in races rated a "toss-up" by Cook Political Report.
Yet candidates didn't need to be in close races to raise millions.
