Is political polarization worse than it's been in the past?

Is polarization really worse than before? I'll gather historical data to compare today's divide with past eras.

In short: Yes, compared to the last 50-80 years - but No, compared to the 19th century.

Political scientists distinguish between types of polarization, and the answer depends on which you mean and what time period you compare to.

1. In the last 50 years, yes - by almost every measure it is worse

Congressional / elite polarization:

A Pew Research Center analysis finds that, on average, Democrats and Republicans are farther apart ideologically today than at any time in the past 50 years.

The analysis is based on DW-NOMINATE, a method that uses lawmakers' roll-call votes to place them in a two-dimensional ideological space. It is designed to produce scores comparable across time.

> Between the 92nd Congress of 1971-72 and the current 117th Congress, both parties in both the House and the Senate have shifted further away from the center, but Republicans more so. House Democrats, for example, moved from about -0.31 to -0.38... House Republicans, by contrast, moved from 0.25 to nearly 0.51

Other findings from that period:

In a longer historical view, the ideological distance between the parties began to grow during the 1970s to the extent that Congress is now more polarized than at any time since the late 1870s Reconstruction Era. Textbooks often phrase it as: Congress is now more polarized than at any time since the end of Reconstruction.

Public / affective polarization - dislike of the other side:

How much Americans dislike each other has risen even faster than differences on issues.

The US stands out globally for the pace of its long-term increase in affective polarization.

Public / issue polarization:

A University of Cambridge Political Psychology Lab study tracking American National Election Studies responses from 1988 to 2024 found:

The study also found sorting has increased: By 2024, 20% more people in the left‑wing cluster now call themselves Democrats, and 51% more call themselves liberals, than in 1988. While 30% more people in the right‑wing cluster now call themselves Republicans, and 39% more are self-described conservatives.

That study shows this polarization may have begun to level off during Biden's term, although it remains far higher than in previous decades.

On the other hand, some political science research argues mass issue polarization is overstated. While elites have polarized, average voters have largely sorted - liberals have become Democrats and conservatives Republicans - without necessarily becoming more extreme on every issue. But on the emotional side, animosity has clearly grown.

2. Compared to the 19th century, no

Historians consistently caution against calling today the most divided time ever:

No political issue in 2020 approaches slavery in the mid-19th century in terms of potential divisiveness, and the Civil War represents a cataclysmic upheaval that current division does not match.

Bottom line

A useful nuance is that the growth has been asymmetric and second-dimension collapse: the second dimension that historically captured cross-cutting issues like civil rights has faded since about 2000, and congressional activity has "collapse[d] into a one-dimensional, near-parliamentary voting structure" where almost every issue is voted along liberal-conservative lines.