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

Your question touches current trends and historical comparisons — I'll search recent research to see how today's political polarization stacks up against the past.

Short answer is: Yes, compared to the last 50-70 years - dramatically so - but not necessarily compared to the most extreme periods of American history, like the Civil War era.

1. Compared to the recent past: Yes, much worse

Multiple measures show polarization is at a modern high.

> Republicans and Democrats are more divided along ideological lines – and partisan antipathy is deeper and more extensive – than at any point in the last two decades.

Pew Research Center's long-running measure based on 10 political values questions found:

> The overall share of Americans who express consistently conservative or consistently liberal opinions has doubled over the past two decades from 10% to 21%

And:

> ideological overlap between the two parties has diminished: Today, 92% of Republicans are to the right of the median Democrat, and 94% of Democrats are to the left of the median Republican.

That compares to just 20 years earlier, when:

> Today, 92% of Republicans are to the right of the median (middle) Democrat, compared with 64% twenty years ago. And 94% of Democrats are to the left of the median Republican, up from 70% in 1994.

Meanwhile the political center has shrunk:

> 39% currently take a roughly equal number of liberal and conservative positions. That is down from about half (49%) of the public in surveys conducted in 1994 and 2004.

Affective polarization - disliking or seeing the other side as a threat, not just disagreeing on issues - has also risen sharply:

> In each party, the share with a highly negative view of the opposing party has more than doubled since 1994.
> In 1994... just 17% had very unfavorable opinions. Similarly... just 16% had very unfavorable views. Since then, highly negative views have more than doubled: 43% of Republicans and 38% of Democrats now view the opposite party in strongly negative terms.

Later data shows it continued to climb:

> In 1994 , only 17% of Republicans and 16% of Democrats reported very unfavorable views of the opposing party. By 2016 , those numbers had risen to 58% of Republicans and 55% of Democrats .

And affective polarization more broadly:

> Dislike of the other party as people, which researchers call affective polarization, has risen in national surveys since the 1980s.

Other analyses reach the same conclusion:

> A Pew Research Center analysis from 2022 found the perception that polarization has increased is correct: Democrats and Republicans are farther apart ideologically today than at any time in the past 50 years.

> "What I've found is that polarization has been steadily getting worse since the early 1970s,"... "Today, we've hit the ceiling on polarization.

The degree is also noted as much higher today when comparing to the 1970s:

> The zeitgeist during the two periods diverged in some ways, notably in the degree of partisan polarization, which is generally considered much higher today.

2. Compared to all of American history: Worst in ~150 years, but not the worst ever

When measured by congressional voting behavior (NOMINATE scores developed by political scientists Keith Poole and Howard Rosenthal), the pattern is U-shaped:

> 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.

Headlines summarize this as:

> Political polarization at its worst since the Civil War

And:

> A new survey from the Pew Research Center reveals that political polarization in the United States has reached a dangerous extreme... We haven't seen such strong polarization since the Civil War.

A concrete measure is the "overlap interval" - how many members of one party overlap ideologically with the other:

> Today, the overlap interval is zero.
> "In the 1960s, for instance, you had intervals where about 50 percent of the legislators in the two parties overlapped."

So in Congress, there are now essentially no liberal Republicans or conservative Democrats, whereas half overlapped in the mid-20th century.

However, historians argue the Civil War era was still more divided:

> According to American political history expert and professor of history Randall Miller, Ph.D., it's not even close. "The most divisive time in our history was in the years leading up to the Civil War," he says. "In the mid-19th Century, differences were so profound representatives carried weapons into Congress."

That period involved actual secession and war, which exceeds current institutional breakdown despite high antipathy.

Some scholars also caution against assuming a simple linear worsening:

> "It's not new. It's unclear if it's worse than in the past, because

The founding era, for example, is seen as comparable in uncertainty:

> Miller does, however, believe our current state of political affairs is comparable to the country's founding. "At the end of the 18th Century, it was the first government under the Constitution. It was a time of great uncertainty — that's the biggest parallel."

3. Important nuance: The majority is not fully polarized

Pew emphasizes that polarization is concentrated among the most politically engaged:

> These trends manifest themselves in myriad ways... And a new survey of 10,000 adults nationwide finds that these divisions are greatest among those who are the most engaged and active in the political process.

And:

> These sentiments are not shared by all – or even most – Americans. The majority do not have uniformly conservative or liberal views. Most do not see either party as a threat to the nation.

But because:

> On measure after measure – whether primary voting, writing letters to officials, volunteering for or donating to a campaign – the most politically polarized are more actively involved in politics, amplifying the voices that are the least willing to see the parties meet each other halfway.

And the center has become disengaged:

> The political center has become increasingly disengaged, ceding the playing field to the most ideological Americans

Historians also point to a qualitative difference today versus earlier eras:

> "During the country's founding, parties were ideologically driven, but they had a middle ground. They agreed on the basics. Today, there is no benefit from compromising. We've created a system that reinforces discord,"

> 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

In sum: If "the past" means the last half-century - the post-World War II, relatively bipartisan middle of the 20th century - then yes, the U.S. is more polarized than at any point since polling began, on both ideological consistency and mutual dislike. If "the past" includes the 1850s-1870s, then current polarization is approaching but has not exceeded that historic peak of national rupture, though it is the highest in about 150 years.