Political polarization in the US is at a high point by many modern measures, but whether it is the worst ever depends on how you measure it.
There are a few different types of polarization researchers track:
1. Elite / Legislative Polarization - Highest in about 100 years
This is the most clearly documented increase.
•Political scientists use DW-NOMINATE scores to measure how ideologically far apart members of Congress vote. By that measure, Congress is more divided now than at any time since the late 1800s / early 1900s.
•There is much less ideological overlap between the parties than 40-50 years ago. In the 1970s-1980s there were many conservative Democrats and liberal Republicans. Today there is almost no overlap in voting records.
•Fewer competitive bipartisan bills and more party-line votes.
2. Affective Polarization - Much higher than in recent decades
This is how much people dislike and distrust the other side, not just disagree on issues.
•Pew Research, ANES, and other long-running surveys show since the mid-1990s, Americans have increasingly viewed the opposing party unfavorably. In 1994, about 16-17% of Republicans and Democrats had a "very unfavorable" view of the other party. By 2022, that was over 40-50%.
•More people now say they would be upset if their child married someone from the other party, and fewer report having close friends across party lines.
•Negative partisanship - voting against the other side rather than for your own - has increased.
3. Mass Ideological Polarization - More nuanced
The average voter is not as ideologically polarized as elected officials.
•Most Americans still identify as moderate or hold a mix of liberal and conservative views on different issues, according to Pew and Gallup.
•What has changed is sorting: liberals are now overwhelmingly Democrats and conservatives are overwhelmingly Republicans, whereas 30-40 years ago both parties had more ideological diversity inside them. People have sorted geographically, too.
•The share of Americans who hold consistently liberal or consistently conservative views across many issues has grown from about 10% in 1994 to about 20-25% now - a significant increase, but still a minority.
In Historical Context:
Compared to the last 50-80 years - roughly the post-World War II era through the 1980s - polarization is significantly worse by almost every measure.
Compared to all of American history, it is not unprecedented. The period leading up to the Civil War, the Reconstruction era, and the late 19th century had higher legislative polarization and, crucially, led to political violence on a scale not seen today.
Common factors researchers cite for the recent increase:
•Partisan media and later social media creating more separated information environments
•Decline of local news and nationalization of politics
•Geographic sorting - people increasingly living near politically like-minded people
•Primary election systems that reward ideological consistency
•Decline in cross-party institutional and social interactions in Congress and elsewhere
In short: If you are comparing to the last two to three generations, yes, polarization is measurably worse. If you are comparing to the 1850s-1860s or 1890s, the country has been more divided before.
Are you asking about polarization in the US specifically, or globally?