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

Polarization is up sharply — I'll compare today's divide to past eras to gauge how it stacks up.

By most modern measures, yes - polarization is worse than at any point in the last 50-70 years, but comparable to the late 19th century.

Political scientists distinguish several types of polarization, and the trends are slightly different for each:

1. What the recent data shows - a sharp increase

In the public:

Researchers at the University of Cambridge using American National Election Studies data between 1988 and 2024 found divisions "were broadly stable through the 1990s and early 2000s, before rising steadily from 2008 onward", estimating that "issue polarization has increased 64%" over that period.

Affective polarization - dislike of the other side:

Scholars are particularly focused on "affective polarisation," the hostility one person feels towards members of the other party relative to their own party.

> Levels of affective polarisation have risen more than two-fold since the 1970s when the American National Election Studies [...] began asking citizens to rate how they felt about members of either major party. In 1978, according to the survey, the difference between Americans’ ratings of members of their own and ratings of members of the other party on a 100-point “feeling thermometer” scale was 27 points. The gap had widened to 56 by 2020.

A cross-national study found that in the U.S., "affective polarization has increased more dramatically since the late 1970s than in the eight other countries they examined—the U.K., Canada, Australia, New Zealand, Germany, Switzerland, Norway and Sweden".

2. Historical comparison - it depends on how far back you look

In Congress - measured by roll-call votes:

Political scientists Keith Poole and Howard Rosenthal's NOMINATE scores scale legislators' liberal-conservative positions based on voting records.

Analysis shows:

> Following a period of a much more balanced Congress during the middle of the 20th century, 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.

More precisely:

> Polarization as measured by the distance between the two major party means declined in both chambers from roughly the beginning of the 20th Century until World War II. It was then fairly stable until the mid 1970s and has been increasing steadily over the past 30 years.

That mid-20th century period was unusually bipartisan:

In that era, "85 percent of votes can be differentiated first and foremost on the basis of party affiliation" today, compared to a two-dimensional system in the 1940s-1960s where northern and southern Democrats often voted differently on civil rights.

Is today an anomaly in 200 years?

> Some political scientists have pointed out that — viewed within the context of data from the last two centuries — today’s levels of polarization are not such an alarming anomaly compared to those occurring during the time of slavery and similar points along the historical continuum.

In other words, polarization today surpasses the previous century's peaks and is at its highest since the Civil War/Reconstruction, but the Civil War era itself - and the intensely polarized late-1870s-1890s Gilded Age - were similarly or more divided.

Researchers also note that elite polarization (in Congress) is more pronounced than mass issue polarization among ordinary voters on many policy issues, and that "Political groups have moved further apart in recent years, but these divisions are still fuzzy, and Americans are not split into entirely opposing tribes when it comes to the issues."

Bottom line