Here I will start with information about longer spans of time, then take up polling data for 2016, 2014, and 2012, compared with earlier results
Partisans’ ratings of Presidents, 1952-2016
One way polarization has been measured is by the difference between partisans in their approval of presidents. In an article titled “Welcome to the golden age of partisanship,” Philip Bump has offered a graph of the gap in presidential approval between parties. It begins with Dwight Eisenhower.
For Eisenhower, the approval gap ranged from 30-40%. If 80% of Republicans approved of Eisenhower and 40% of Democrats approved, the gap would be 40%. To my eye, the gaps rise for Ronald Reagan, George HW Bush and Bill Clinton, and then rise again for George W Bush and Barack Obama. The gaps for Bush ranged from about 45% to about 70%. The gaps for Obama range from a bit more than 60% to about 75%. A gap of 75% would be produced, for example, by 90% approval among Democrats and 15% approval among Republicans.
Polarization in the Congress
In the Washington Post, Christopher Ingraham provide “A stunning visualization of our divided Congress” from 1949 to 2011. I agree the visual is stunning and well worth taking the time to look at. Regarding it, Ingraham comments:
Similar voting between Democrats and Republicans was fairly common up through the 1980s. But starting in the 1990s the parties began pulling apart from each other, like a single cell dividing into two.
Not only that, but within parties Representatives are voting more similarly too — that’s illustrated with the dots in each party’s cluster becoming more tightly packed together over time. Starting in the 2000s, there are hardly any links between the parties at all.
Partisan animosity in 2016
In March and April of 2016, the Pew Research Center surveyed 4,385 members of its American Trends Panel study. According to the June report:
The 2016 campaign is unfolding against a backdrop of intense partisan division and animosity. Partisans’ views of the opposing party are now more negative than at any point in nearly a quarter of a century.
For the first time in surveys dating to 1992, majorities in both parties express not just unfavorable but very unfavorable views of the other party. And today, sizable shares of both Democrats and Republicans say the other party stirs feelings of not just frustration, but fear and anger…
Across a number of realms, negative feelings about the opposing party are as powerful – and in many cases more powerful – as are positive feelings about one’s own party. (Pew Research Center, June 2016, emphasis in original)
Those negative appraisals go so far as to say that the other party is a “threat”:
45% of Republicans now view Democratic policies as a threat, up from 37% in 2014. And 41% of Democrats say the same about the Republican Party’s policies, an increase of 10 percentage points from two years ago. (Pew Research Center, June 2016)
Respondents had definite opinions about members of the other party, in comparison to members of their own:
Fully 70% of Democrats say that Republicans are more closed-minded than other Americans. And nearly as many Democrats (67%) say the people in their party are more open-minded than other Americans.
Fewer Democrats (42%) say Republicans are more dishonest than other Americans, 35% say they are more immoral and 33% say they are more unintelligent.
Many Republicans, by contrast, think Democrats fall short on several traits. While more than half of Republicans (52%) view Democrats as more closed-minded than other Americans, nearly as many say Democrats are more immoral (47%), lazier (46%) and more dishonest (45%).
Not only do almost half of Republicans say Democrats are lazier than other Americans, most (59%) also say the members of their own party are more hard-working. And about half of Republicans (51%) view Republicans as more moral than other Americans. (Pew Research Center, June 2016)
Perhaps the clearest result here is this: When we consider what evidence the respondents would need to back their claims, they cannot possibly know what they are talking about. This willingness to go far beyond evidence to criticize members of the other party signals some kind of disdain, contempt, or disapproval that is disconnected from evidence. And, compared to responses to the same questions in earlier surveys, that hostile mood is stronger in 2016 than it was as recently as 2014.
Party, ideology, and animosity, June, 2014
In June of 2014, Pew issued a report titled “Political Polarization in the American Public”. It found ideological thinking strengthened and more closely aligned with party.
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 thinking is now much more closely aligned with partisanship than in the past. As a result, 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.
Partisan animosity has increased substantially over the same period. In each party, the share with a highly negative view of the opposing party has more than doubled since 1994. Most of these intense partisans believe the opposing party’s policies “are so misguided that they threaten the nation’s well-being.” (Pew Research Center June 2014)
Polarization in action, October, 2014
In October of 2014, Pew issued another report, titled “Political Polarization in Action”.
Hostility toward the opposing party is a key marker of polarization and a strong motivator for voting, especially among Republicans. Both Republicans and Democrats have long held negative views of the opposite party. But the level of partisan hostility has grown dramatically in the past 20 years. (Pew Research Center, October 2014).
One idea that stands out in the October 2014 report is that those who are most ideological and most partisan, also are most hostile to the other party, and that hostility moves them to vote.
Hostility to the opposing party is a key marker of polarization and is a strong motivator to vote, especially among conservatives and Republicans. Ideology and partisan antipathy are related: Those holding ideologically consistent opinions are far more likely than others to view the opposing party negatively, and even to view it as a threat to the nation’s well-being. (Pew Research Center, October 2014)
The most consistently ideological voters also are most likely to vote a straight party ticket:
Nearly nine-in-ten (87%) with consistently conservative views choose Republican candidates down the line, while 84% of those with consistently liberal views choose a straight Democratic ticket…. Even among voters with ideologically mixed views, most (61%) still choose a slate of candidates from one party; 18% split their tickets between parties. (Pew Research Center, October 2014)
Most independents also have partisan leanings; they tend to respond to the surveys much like members of the parties.
So, over the past 25 years, the major parties have grown smaller, more ideological, and more hostile to each other. Many independents are “leaners” toward one party or the other, and tend to respond to surveys much like the members of the party to which they lean.
Partisan polarization surges, 2012
Is it possible to identify a time when our polarization began to increase? If we could see a time, we might also see events that contributed to polarization. On that question, I found different estimates from different sources, from “decades” and “since the 1970’s” to “in the Bush and Obama years.”
“Partisan Polarization Surges in Bush, Obama Years.” That was the headline of a Pew Research Center report issued in 2012. It pointed to an increasing gap between Republicans and Democrats on a survey of “basic values and beliefs.”
As Americans head to the polls this November, their values and basic beliefs are more polarized along partisan lines than at any point in the past 25 years. Unlike in 1987, when this series of surveys began, the values gap between Republicans and Democrats is now greater than gender, age, race or class divides.
Overall, there has been much more stability than change across the 48 political values measures that the Pew Research Center has tracked since 1987. But the average partisan gap has nearly doubled over this 25-year period – from 10 percentage points in 1987 to 18 percentage points in the new study.
Nearly all of the increases have occurred during the presidencies of George W. Bush and Barack Obama. During this period, both parties’ bases have often been critical of their parties for not standing up for their traditional positions. Currently, 71% of Republicans and 58% of Democrats say their parties have not done a good job in this regard. (Pew Research Center, 2012)
That last finding is striking: The last two decades are period of marked gridlock in the Congress, yet the party bases criticize the paraties for “not standing up.”
We sort ourselves into the parties, 1987-2012
Again from the 2012 Pew report: In the same period as party division and hostility was growing, both parties were shrinking and the proportion of self-identified independents was growing.
While Republicans and Democrats have been moving further apart in their beliefs, both groups have also been shrinking. Pew Research Center polling conducted so far in 2012 has found fewer Americans affiliating with one of the major parties than at any point in the past 25 years. And looking at data from Gallup going back to 1939, it is safe to say that there are more political independents in 2012 than at any point in the last 75 years. (Pew Research Center, 2012)
At the same time, the parties were separating in their demographic composition:
Demographically, Republicans remain overwhelmingly white and their average age now approaches 50. Fully 87% of Republicans are non-Hispanic whites, a figure which has changed little since 2000.
Meanwhile, the percentage of Democrats who say their political views are liberal has risen from 28% in 2000 to 34% in 2008 and 38% in 2012 surveys by the Pew Research Center. For the first time, there are as many liberal Democrats as moderate Democrats.
In contrast to Republicans, Democrats have grown increasingly diverse. A narrow majority of Democrats (55%) are non-Hispanic whites, down from 64% in 2000. As in recent years, most Democrats are women (59%). And while the average age of self-described Democrats has risen since 2008 – from 46.9 to 47.7 – Democrats continue to be younger than Republicans on average (47.7 vs. 49.7). (Pew Research Center, 2012)
It appeared that most self-identified independents lean toward one party or the other, and the leaners were more polarized than in the past.
Yet political polarization is not limited to the narrowed partisan bases. Even independents who say they only lean toward one or the other party have grown further apart in their values and beliefs.
This is a very interesting finding. While the parties are shrinking because the proportion of voters who identify themselves as independents is increasing, most of those independents tend to have ideological and other views similar to those of the party they lean toward. Why? One possibility is that they are discouraged, put off, or even offended by the increasingly rancorous tone and content of the partisan dispute, by the constant bickering between parties, and by their failure to work together. While they have an ideological preference, they distance themselves from the partisan conflict.
Adding it up
Large proportions of Republicans and Democrats are afflicted by some malady that enables them, or encourages them, or even requires them, to look at the same situations, to come up with entirely different sets of facts and opinions about those situations, and then to engage in fruitless hostility.
These people are in danger of losing their minds, and they are endangering the United States of America. Locked together in their conflict, they are collaborating to wreck our politics, much as a fight between two powerful drunks can wreck a bar. Civil discussion of issues cannot occur when the polarized partisans are present. In the midst of their shouting, it is difficult even to hear ourselves think, much less hear other reasonable people who are talking in a normal tone of voice.
The malady is “polarization.” The longer-term evidence suggests that this problem has been building since the mid-1970s, and that it has grown much worse in the last 25 years. At its heart appears to be sorting, which lines up party identities with ideological identities, social identities, geographic identities, and so on, until many us many of our important eggs in the same party basket. Having too many eggs in party baskets tends to produce strong feelings, animosity, mistrust, and even hatred between the members of the parties, which makes the whole thing worse.
All of this is dangerous. How can we succeed as nation when we are in this strongly divided state?
Polarized Partisanship 