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

Is polarization really worse than before? I'll pull the historical evidence and current data to compare.

Is political polarization worse than in the past? The answer depends on what time period and what type of polarization you mean:

Yes - Compared to the last 50-150 years of modern polling and congressional data, polarization is at a historic high

Among voters and the public:

> Start with the voters...it clearly shows that self-described conservatives make up a greater share of Republicans in 2012 (68%) than they did in 2000 (59%), while self-described liberals account for a greater share of Democrats (27% in 2000, 39% in 2012)

> Across 48 different questions covering values about government, foreign policy, social and economic issues and other realms, the average difference between the opinions of Republicans and Democrats now stands at 18 percentage points…nearly twice the size of the gap in surveys conducted from 1987-2002.

Pew Research Center analysis found that way:

> Democrats and Republicans are farther apart ideologically today than at any time in the past 50 years.

And Pew described it as:

> Partisan polarization, in Congress and among public, is greater than ever

Affective polarization - how much partisans dislike the other side:

> Affective polarization in the United States – the gap between individuals’ positive feelings toward their own political party and negative feelings toward the opposing party – has increased markedly in the past two decades.

In a cross-country study of 9 democracies from 1975-2017:

> Over the past four decades, the chilly chasm of negative sentiment between Democrats and Republicans in the U.S. has nearly doubled, and it has grown faster and larger compared to the partisan climates of eight other established democracies

The study measured the feeling-thermometer gap:

> in 1978, the average gap of negative sentiment between Democrats and Republicans was 27 points. By 2016, that difference grew to 46.

Among political elites in Congress:

> Political elites of the United States are deeply polarized. Polarization of the Democratic and Republican Parties is higher than at any time since the end of the Civil War.

Following a period of more balanced Congress in the middle 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.

That pattern is measured with DW-NOMINATE scores, based on legislators' voting records. The analysis shows:

> Both parties have grown more ideologically cohesive. There are now only about two dozen moderate Democrats and Republicans left on Capitol Hill, versus more than 160 in 1971-72.

> 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.

Another measure is the overlap interval - how many Republicans are to the left of the most conservative Democrat and vice versa:

> This measure shows how many Republicans lie to the right of the most right-leaning Democrat and how many Democrats lie to the left of the most left-leaning Republicans. Today, the overlap interval is zero.

> “This was certainly not always true,” ... “In the 1960s, for instance, you had intervals where about 50 percent of the legislators in the two parties overlapped.”

More specifically:

> Since 2002, when Republican Rep. Constance Morella of Maryland was defeated for reelection and GOP Rep. Benjamin Gilman of New York retired, there’s been no overlap at all between the least liberal Democrats and the least conservative Republicans in the House.

And researchers note:

> Because the NOMINATE data ... shows that partisan elites in the U.S. are as polarized today as they were around the time of the Civil War, it suggests that there is a huge gulf in the middle that’s not being responded to by the two parties

The U.S. also stands out internationally:

> America’s widening political divide stands out above other nations, according to a new cross-country polarization study

No - Compared to the most divisive periods in American history, today is not the worst

Historians point to the Civil War era as more divided:

> As a historian who has written and taught about the Civil War era for several decades, I know that current divisions pale in comparison to those of the mid-19th century.

> Between Abraham Lincoln’s election in November 1860 and the surrender of Robert E. Lee’s Confederate army at Appomattox in April 1865, the nation literally broke apart.

That conflict produced:

> Four years of civil war produced at least 620,000 military deaths – the equivalent of approximately 6.5 million dead in the United States of 2020.

Other eras also saw higher levels of violent conflict than today. Some analyses note:

> for all the hype about the ruptures and partisan rancor in contemporary American society, the strife pales in comparison with much of the nation’s past. There have been long stretches of American history in which conflicts were far worse.

Examples historians cite include slavery and its expansion as an intractable issue, the caning of Senator Charles Sumner on the Senate floor in 1856, the secession of seven slaveholding states between 1860-1861, and later periods such as racial apartheid after slavery and the urban riots and anti-war protests of the 1960s.

Bottom line