Despite some high-profile exceptions, most 2018 contests were driven by straight-ticket voting. Illustration: Intelligencer; Maxicam/Getty Images

There’s a long-standing conceit in America’s political culture that holds up ticket-splitting as the sign of an intelligent, discerning voter. “I vote for the candidate, not the party” has been the proud boast of many a civically active do-gooder, who regarded straight-ticket voting as the sign of the benighted or the fanatic. And the prejudice does live on in the high level of voters who choose to self-identify as independents, even though a majority of them vote pretty much like the partisans they disdain.

In reality, serious ticket-splitting has been declining for decades. The primary reason has been the ideological sorting-out of the two major parties that accelerated with the civil rights revolution, and culminated with the conquest of the Republican Party by the modern conservative movement while left-of-center voters and candidates increasingly voted for Democrats. It all took a while to evolve: as recently as the 1980s, there remained a significant number of self-identified liberal Republicans and conservative Democrats serving in Congress and state offices. In my own youth in Georgia, the ballot offered a sub-presidential straight ticket ballot line so that white conservatives could vote for the Republican presidential candidate and then vote Democratic for everything else. There wasn’t a lot of discernment going on; it was really just a matter of persistent ideological distinctions between national and state parties.

Outside a few pockets in Appalachia and New England, that’s all pretty much a thing of the past. By 2016, Jeff Stein felt justified in declaring ticket-splitting “dead:”

Every single state that elected a Republican senator this November voted for Donald Trump — and every single state that elected a Democratic senator voted for Hillary Clinton.

That’s a first in American history — at least going back to 1913, when the Constitution began mandating the direct popular election of senators. And it’s a dramatic reversal from much of the middle of the 20th century, when voters frequently backed senators of one party while also supporting the opposing party’s presidential nominee — a phenomenon known as ‘ticket splitting.’

Straight-ticket voting has been reinforced by another phenomenon that has found its full sinister flowering in the Trump Era: the identification of parties with the candidate on the very top of the ballot:

[A] study by professor Steven Rogers of St. Louis University … found that the single most important factor in state legislature races is what the voters think of the sitting president — even if the president has essentially no hand in setting statehouse policy.

Voters are about six percent more likely to vote against their state lawmaker if they disapprove of their state legislature, about nine percent more likely to do so if they disapprove of their governor, and a full 40 percent more likely to vote against the president, according to Rogers.

The president is not literally on the ballot in midterms, which makes it a bit easier for down-ballot candidates to show independence from their party. But most don’t, for reasons of ideological consistency, the tribal inclinations of voters and lawmakers alike, and for Republicans, the intense pressure created by Trump and his supporters to support MAGA (and for Democrats, to oppose it). Yes, you still see a few signs of trans-partisanship from candidates running in hostile territory, like the House Democrats who campaigned in 2018 promising to dump Nancy Pelosi, or the Republicans who found one or two unpopular Trump policies to oppose. But compared to the not-so-distant past when you sometimes couldn’t tell the parties apart at the state and local levels, the partisan polarization everyone talks about is very real and pervasive.

This rule can be obscured by the excessive attention paid to the rare exceptions. In 2018, that would be the Republican governors of blue states in the northeast, like Phil Scott of Vermont, Charlie Baker of Massachusetts, and Larry Hogan of Maryland; and the surviving Democratic red-state senators like Jon Tester of Montana and Joe Manchin of West Virginia. Geoffrey Skelley took a long look at gubernatorial and Senate races in 2018, and concluded that despite these outliers, ticket-splitting between the top two candidates on the ballot in this midterm remained historically very low:

It turns out that 2018 is part of a trend that shows fewer Americans are splitting their tickets (at least in races for the Senate and governors in midterm elections). This election had the smallest median difference of any midterm cycle going back to at least 1990 — 10 points.

Incumbency, Skelley noted, could blunt some partisan pressures. As candidates like Baker and Manchin finally retire, they will very likely be succeeded by members of the dominant (Democratic and Republican, respectively) parties of their states.

Straight-ticket voting is even more prevalent in U.S. House races. All those Democrats winning “Republican districts” that we heard about were not beneficiaries of ticket-splitting: it just happened to be a year in which turnout patterns and actual party-switching (which could be temporary or permanent; we don’t know just yet) tilted the entire landscape towards the donkey ticket. As Nathaniel Rakich notes, House races were very predictable once you took that into account and factored in each district’s established partisan “lean” in recent elections:

If you wanted to predict the results of the 2018 midterm elections, you could have done a lot worse than simply adding the generic-ballot average to each district’s partisan lean. The average Democratic candidate in a contested House district outperformed his or her district’s partisan lean by 7.3 percentage points, which almost exactly mirrors the national House popular vote.

Sure, there were variations, and in many states enough differences between the performance of different candidates that it’s clear ticket-splitters aren’t gone altogether. But the prevailing trend was exhibited in what used to be the heartland of ticket-splitting, the South. In Georgia, the Republican candidates for six statewide offices received between 49.09 percent and 52.46 percent. Two overachieving outliers won 53 percent. In Florida three of five statewide Republican candidates got right at or just under 50 percent of the vote; the fourth and fifth got 52 percent. That’s hardly surprising now that Democrats in these states tend not to run against the national party, and are reliably center-left on issues, while Republicans almost all adore Donald Trump. Don’t expect ticket-splitting to come back in 2020, when the master of polarization runs for reelection.