In the debate over “polarization” that’s roiled the commentariat this week, one particular point of contention is whether partisan polarization is bad for the country, or in some other sense “abnormal.” Yesterday Ezra Klein cited an analysis of congressional voting patterns from the late nineteenth century until recently to argue that “bipartisanship” is the anamoly:

This halcyon era of bipartisanship was a short blip that was primarily the product of a grotesque alliance between the anti-civil rights Dixiecrats and the conservative Republicans who would eventually absorb them. There’s very little to fondly recall about that.

But I think the story is a bit more complicated than this “short blip” interpretation would suggest. The data Ezra cites involves average voting differences between congressional Democrats and Republicans at any given time: average is the key word here. That’s a very different proposition than the sort of suspend-the-differences, hands-across-the-water connotations of the word “bipartisanship. From the 1940s through the 1970s, there was plenty of polarization in Washington; but it didn’t nicely comport with party lines. Some of the polarization was internal, within the parties, and some was between the parties, or external, depending on the issue. And you can certainly make the argument historically that party realignment occurs when internal polarization comes to outweigh external polarization.
During the civil rights era, for example, it’s not as though party differences disappeared; on the role of the federal government in economic life, there was a relatively stable divide between Ds and Rs regardless of region, with some variations. But on the issues related to civil rights, the alignment of southern conservative Democrats and conservative midwestern and western Republicans eventually became more important than the differences on other issues (including economics) that had long divided them. Because a similiar dynamic was underway that united non-southern Democrats and northeastern Republicans, the imbalance between internal and external polarization produced a party realignment and the ideologically homogenous parties we perceive as “normal” today.
The same thing’s happened at other points in American political history. Most famously, prior to the Civil War the Democrats and Whigs were quite polarized externally over tariff and banking policies. But on slavery, and even on the foreign policy issues (e.g., the Mexican War) that were influenced by the slavery issue, each party was internally polarized. This untenable situation led to the creation of the Republican Party, which absorbed non-southern Whigs and many non-southern Democrats, even as southern Whigs drifted into the Democratic Party and stayed there for another century.
Similarly, in the late nineteenth century, there was lots of polarization: we had some of the most savagely fought elections, with among the highest turnout levels, in U.S. history, although the two parties were mainly polarized over the tariff, patronage, and the residual racial issues left over from Reconstruction. Economic dislocations produced a growing internal polarization in both parties over monetary policy, farm policy, and regulation of corporations, and in 1896, a realignment began to occur, though this time it occured between the existing major parties rather than through the birth of a new party system.
I could go on and on, but the main point here is that ideological and partisan polarization has always existed, as has agreement across party lines, depending on which issue dominated the national agenda, generated votes in Congress, and influenced national, and particularly presidential, elections. Perceptions of polarization and bipartisanship are often made in hindsight, when the issues that dominate one period of political history are read back into the dynamics of the previous era. The partisans of the 1880s would have been shocked to discover that their successors mostly viewed their violent disagreements as trivial. And the partisans of the 1840s and would have similarly shocked at the subsequent view that the Democratic and Whig parties of that time were contrivances that existed simply to paper over the “real” battle over slavery that raged just under the surface.
In other words, we may not know for some time whether today’s partisan polarization is stable and semi-permanent, much less “normal.” So all the arguments in favor of or opposed to “bipartisanship” or “polarization” in the abstract may ultimately miss the point.