Repair-It

The right has moved to the right, and the left has moved to the left.

A lot of folks are insisting that one or the other of these has happened, but that's really only possible by cherry-picking issues to match to the arguer's preferred conclusion.

Both sides have lost some battles which only extreme activists are attempting to reverse. For example, Clinton capitulated to welfare reform in the '90s, and that moved the Democrats to the right. But the GOP has effectively lost the battle on same-sex marriage, which moved the Republicans to the left. Yes, both parties still claim to be fighting those, but no reasonable observer expects anything to happen or much real energy to be extended other than political theater.

The xkcd diagram provided in Richard Gaushell's answer is a little open to interpretation, but my reading tells me the two parties remain in a rough balance. Another excellent source is the animated diagram in the New York Times article, Polarization Is Dividing American Society, Not Just Politics and the Pew Research Center study that article drew upon.

democrat republican liberal conservative overlap.JPG

What is causing this? Two big factors.

The first is that we're increasingly distancing ourselves socially from those that we don't agree with. Through most of history, people lived near where their relatives lived and worked, and associated with neighbors — association by propinquity. The increased mobility of Americans in the past fifty years or so has us living where we want, with the result that we are "sorting" ourselves by preferences which happen to have a large correlation with political affiliation. For example, liberals have a slightly higher tendency towards openness to new and varied experiences, and are drawn towards cities. Conservatives have a slightly higher tendency towards caution with respect to new experiences, and their mild tendency to keep the world at arm's length means they're drawn to suburbs, exurbs and rural communities. Increasingly, we don't physically live near our partisan rivals.

This is called demographic clustering, and leaves us geographically out of contact with those that hold other views. This is covered in greater depth in the 2008 book, The Big Sort: Why the Clustering of Like-Minded America Is Tearing Us Apart.

This is also taking place on social media. It is likely that those you interact with on the internet are also members of your partisan tribe, and to the extent that others are mixed in, it is likely that less of your conversation with them is about partisan issues. We are, quite simply, tribal when it comes to morality and politics.[1]

In sociology, the Contact hypothesis relates to how disparate populations can adapt to one another and get along. Of course, "contact" implies that they must interact; the fact that our population is doing that less and less means we simply not only don't agree with our opponents, we don't even spend time with them as humans, which tends to make their views seem extreme and unlikely.

This is why the protesters that took over Malheur National Wildlife Refuge in early 2016 sometimes appeared baffled at the hostility implied by the gag shipments they received. It also explains why many of Bernie Sander's supporters in the Presidential primary don't recognize that the "revolution" his campaign promises is likely to hit the same roadblocks that Obama's "Change" platform ran into after his election. Neither group associates with their opponents, and so underestimates the breadth of political debate and their chances of success. In another example, in 2004, the playwright Arthur Miller wrote, “How can the polls be neck and neck, when I don’t know one Bush supporter?” Or, as asked here on Quora, "Why don't I know any liberals?"

The second factor amplifies this first one. The explosion in media sources since the creation of cable television, first, and then more so with the internet means that we have instant and pervasive information about what is happening in the political system.

In previous centuries, information that detailed took too long to gather for most people, and was available only to the political elites. What information flowed to the population at large as heavily filtered, as anyone who recalls how reassuringly bland television news was before cable broke that paradigm.

Now, people are informed instantly, and at depth, and through channels that that tend to reflect their own preferences. Because we perceive our own preferences very strongly, and the much more abstract concept of "making sure things work" relatively weakly, the pressure on political representatives has been to become correspondingly ideological.

presidential approval by party over time.JPG

(See the Pew Research Center article on Presidential job approval ratings from Ike to Obama as well as other Pew Research on Political Polarization.)

This has also distorted the electoral primary system into an ideological gantlet that punishes politicians who represent pragmatism. The 2016 GOP Presidential Primary has illustrated this, with the non-extreme candidates completely marginalized.

This appears to be a consequence of various cognitive biases humans are heir to combined with changes in our media environment from recent decades. There is no indication if or when conditions will return to the previous state.

If 58 percent of Republicans hate Democrats and 55 percent of Democrats hate Republicans, that would mean about 35 percent of registered voters hate the opposite political party.

Of course, that's not 35 percent of the entire U.S. population of 320-or-so million; it's just 35 percent of all registered voters. And according to Tom Bonier of the Democratic political data firm TargetSmart, the country surpassed 200 million registered voters just before the 2016 election. Using that number, you have about 70 million Republicans and Democrats who hate the other political party.

In this case, 45 percent of Republicans hate the Democrats, and 41 percent of Democrats hate the Republicans. That's 26.5 percent of all registered voters, or about 53 million people in total.

That's not the final number, though. You also have some independents who hate one political party but don't necessarily see fit to join the opposite party. I asked Pew about this, and it sent over some numbers: 18 percent of independents see the GOP as a threat, and 19 percent see the Democratic Party as a threat. Applying that to the 34 percent of registered voters who describe themselves as independents, and there's another 25 million people who hate one side or another, for a grand total of 78 million.

So in the end, only about 78 million Americans actually hate the other political party — not 320 million. That's only one-fourth of the entire population! (Of course, it also includes little babies who may or may not have the capacity for deep-seated hatred. Yet.)

Maybe we don't need secession after all?