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

Is polarization worse than ever? I'll pull the latest data on how divided we are now compared to past eras.

Yes - by most measures used by political scientists, polarization today is worse than at any point in the last 50 years, but not necessarily worse than at all points in U.S. history. The answer depends on what you measure and what period you compare it to.

Evidence that it is worse than the recent past

1. Affective polarization - how much partisans dislike the other side - has nearly doubled:

> Over the past four decades, the chilly chasm of negative sentiment between Democrats and Republicans in the U.S. has nearly doubled

Stanford economists using thermometer ratings from 1975-2017 found:

> in 1978, the average gap of negative sentiment between Democrats and Republicans was 27 points. By 2016, that difference grew to 46

That increase was larger and faster in the U.S. than in eight other democracies studied:

> affective polarization has increased more dramatically since the late 1970s than in the eight other countries they examined

In three other nations — Canada, New Zealand and Switzerland — political polarization rose as well but to a lesser extent. During the same period, polarization decreased in the five other countries — Australia, Britain, Norway, Sweden and Germany.

2. Ideological consistency and sorting in the public has increased since the 1990s:

Pew Research Center combined responses to 10 political values questions asked since 1994 to create a measure of ideological consistency:

> Over the past twenty years, the number of Americans in the “tails” of this ideological distribution has doubled from 10% to 21%

And:

> self-described conservatives make up a greater share of Republicans in 2012 (68%) than they did in 2000 (59%), while self-described liberals account for a greater share of Democrats (27% in 2000, 39% in 2012)

> Across 48 different questions covering values about government, foreign policy, social and economic issues and other realms, the average difference between the opinions of Republicans and Democrats now stands at 18 percentage points…nearly twice the size of the gap in surveys conducted from 1987-2002

Researchers note previous research suggesting polarization in the United States is more pronounced now than in the past -- at least among members of the nation’s major political parties -- with Democrats significantly more likely to identify as liberal and Republicans as conservative.

3. Elite polarization in Congress is at a 100+ year high:

Political scientists using DW-NOMINATE scores - which estimate ideology from roll-call voting records - find:

> Political elites of the United States are deeply polarized. Polarization of the Democratic and Republican Parties is higher than at any time since the end of the Civil War

> 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

Specifically:

> the parties began to diverge in the mid-1970s and this trend has continued unabated into the most recent Congress

One way to see this is the overlap interval - how many Republicans are to the left of the most conservative Democrat and vice versa:

> 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

Why it is not simply "the worst ever"

Historians and political scientists caution that the mid-20th century was an unusually low polarization period, and the comparison matters:

> Any serious exploration of today’s political polarities has to be placed in historical context. We have to ask: Compared to what?

> Today’s social conflicts and partisan strife pale in comparison with much of the nation’s past. Recall the racial apartheid that scarred America for a century after the end of slavery, and the urban riots and anti-war protests that inflamed the country during the 1960s

Some historians argue the Civil War era was more divisive:

> The most divisive time in our history was in the years leading up to the Civil War
> In the mid-19th Century, differences were so profound representatives carried weapons into Congress

And:

> As a historian who has written and taught about the Civil War era for several decades, I know that current divisions pale in comparison to those of the mid-19th century

Scholars also distinguish between elite vs. mass polarization and polarization vs. sorting:

> Properly defined, polarization of U.S. politics reflects a sorting of political convictions by either the mass public or ruling elites, or both, into roughly two distinct camps

Research by Morris Fiorina and others argues that while elites and activists have polarized sharply since the 1970s, the mass public has largely undergone sorting - liberals becoming Democrats and conservatives becoming Republicans - rather than the average American moving to ideological extremes. The bulk of voters still hold mixed views, but those views now align more consistently with party identity.

Bottom line