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How politically divided is the U.S.? It’s complicated but quantifiable.

Our new measure of national unity examines shifts over decades

- June 6, 2022

According to the prevailing national narrative, American unity is at or near an all-time low.

There is certainly reason to believe so. You can see anecdotal evidence of extreme, possibly growing polarization every day, simply by opening your Twitter feed. Even so, we do not have good, systematic evidence about national unity — or, more important, about how it may have changed over time. Relying on social media to form an opinion is ill-advised, given its algorithmic tendency to mislead; social media feeds on itself and often makes users feel angrier and more disenchanted.

To overcome this, we sought to develop something more objective. The Vanderbilt Project on Unity and American Democracy has launched the Vanderbilt Unity Index (VUI) to estimate the state of U.S. unity. The goal is to measure unity in a systematic, replicable and reliable way. We find that while some political disunity is endemic to the contemporary United States, the country may not be as fragmented and polarized as the prevailing narrative suggests.

The Vanderbilt Unity Index

The VUI tracks quarterly shifts in national unity since 1981 by aggregating publicly available data across five categories: presidential disapproval, ideological extremism, social trust, congressional polarization and civil unrest.

Our work aims to capture the extremes. For instance, we record the percentage of Americans who strongly disapprove of the president, as collected by the Gallup Poll, rather than overall disapproval of the president. We also incorporate the share of Americans who identify as strong liberals or conservatives, from various pollsters, as well as those who report to NORC’s General Social Survey that they do not trust most people. The VUI takes account of the ideological distance between congressional parties as calculated by political scientists at VoteView. Finally, we capture the extent of notable political unrest by recording the number of questions asked regarding political protest or unrest by several major pollsters, including Gallup, Pew and NBC. This composite thus allows us to assess U.S. unity by looking for patterns and trends over the past 40 years, without relying on pundits’ hyperbole and hand-wringing.

We then scaled each of these five factors to range from 0 to 100, where higher values indicate greater political unity, and then combined the factors with equal weight and normalized the measure to a maximum score of 100. After analyzing and plotting 165 calendar quarters on a 100-point scale, we can report that the country, even after the terrorist attacks on 9/11, has not been close to “unified” — at least, if we define unity as unanimity. In theory, a score of 100 might indicate perfect unity, while a score of 0 might indicate complete division. But the scores are best understood as revealing general shifts and trends rather than as absolute measurements of national unity at any precise moment.

During the period we studied, we found the highest level of unity — 71.3 — was during the second quarter of 1991, as Americans were rallying behind George H.W. Bush in the wake of the Persian Gulf War. We also discovered that the modern United States has had only rare moments of politically unity. Since 1981, the index surpassed 70 only 12 times, or just 7 percent of the quarters we measured. Similarly, our most divided moments have not been as bleak as conventional political wisdom might suggest: Of the 165 quarters we tracked, only in three did the unity score fall below 50.

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Data and figure: Vanderbilt Project on Unity & American Democracy
Data and figure: Vanderbilt Project on Unity & American Democracy

However, the VUI does clearly find that unity has been declining over the past three decades. As you can see in the figure above, the VUI began moving downward in 1995; from 1995 to 2022, the index has averaged around 59, less than the average VUI of 68 from 1981 to 1994.

The shift squares with conventional wisdom. Newt Gingrich’s Contract with America, launched during the campaign before the 1994 midterm elections, ushered in an era in which the parties “nationalized” congressional races, a term political scientists use to indicate the centrality of national and presidential politics in shaping congressional election outcomes. Meanwhile, the culture wars were heating up, fanned by the 1996 launch of partisan news outlets Fox News and MSNBC. A decade later came the vice-presidential candidacy of Sarah Palin, the presidential election of Barack Obama and the rise of the tea party.

Finally, we see populist figures like Bernie Sanders on the left and Donald Trump on the right — and, with Trump’s presidency, nine of the 10 lowest VUI scores that we measured over this period, setting a record low of 35 in 2017. The 10th came in the quarter before Trump was elected in 2016. From this, we conclude that efforts to undermine democratic institutions through oft-repeated false and misleading rhetoric endanger the idea of “e pluribus unum” — out of many, one.

The VUI’s most recent quarterly snapshots suggest that some of the country’s disharmony may be dissipating. The first five quarters of the Biden administration show an average of 58, a notable increase from the average VUI of 51 during the Trump era.

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Unity is not unanimity

Overall, the VUI measure confirms the thesis of biographer, historian and Project on Unity and American Democracy co-chair Jon Meacham in his 2019 book “The Soul of America”: “Disagreement and debate — including ferocious disagreement and exhausting debate — are hallmarks of American politics. …. The art of politics lies in the manufacturing of a workable consensus for a given time — not unanimity.”

U.S. democracy, in other words, is about managing disagreement. Americans have never been fully unified. The Founders crafted the Constitution knowing that citizens naturally disagree.

By subjecting our recent past to statistical analysis, the VUI demonstrates that the country has rarely been as unified as citizens like to imagine. It also offers a basis for comparison going forward. The VUI confirms that Americans are less unified today than 40 years ago, a worrisome pattern. Since 1981, the VUI has averaged about 62. As of March 31, 2022, the index stands at a little over 57 — and has been rising. Perhaps the path to a more unified country is not out of reach.

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John Geer (@JGGeer) is a professor of political science, the Ginny and Conner Searcy Dean of the College of Arts and Science at Vanderbilt University, which houses the Vanderbilt Project on Unity and American Democracy, and co-director of the Vanderbilt Poll.

Mary Catherine Sullivan (@mcsullivann) is a PhD candidate in political science at Vanderbilt University.