This post is part of Polyarchy , an independent blog produced by the political reform program at New America , a Washington think tank devoted to developing new ideas and new voices.

Yesterday, I published a big essay on Vox in which I argued that the current variant of hyperpartisanship is breaking American democracy. Our political institutions are just not set up to handle two deeply polarized, highly competitive political parties. And the current partisan division — in which racial, cultural, and geographical identities all line up with partisan allegiances — is just deadly for democratic compromise, since it organizes politics around a set of national identity issues where compromise is impossible.

Moreover, because our national elections are so tightly contested, majority control is always in reach or in danger for both parties. This breeds a particularly nasty zero-sum type of politics, in which compromise becomes difficult to impossible: Why help the other party when your electoral success depends on their failure?

In my essay, I argued that one way to dissolve this destructive zero-sum trench warfare would be to move to a multiparty system by changing electoral laws, thus effectively ending the two-party system that has been a marked feature of American politics for our entire political history — a function of our single-member district, plurality-winner approach to elections.

But this raises an obvious question: If our system of elections is so bad, how did we survive as a highly functioning democracy for as long as we have?

The answer is that something is very different about this era American politics. We have a highly unusual pattern of partisan competition, a pattern we’ve never quite had to these extreme levels.

Nationally, the parties are roughly equally competitive, to a historically remarkable degree. But regionally, parties are mostly noncompetitive, also to a historically remarkable degree.

Putting today in broader historical context

Just how unusual is our current era in American politics? Let’s start with the below chart, which tracks the percentage of states that have voted for the same party for president for five consecutive elections, culminating with a particular election. (I only go back to the post-Civil War period, since the party system before the Civil War was different and more fluid.)

With the election of 2016, the share of states that had supported the same party for five consecutive presidential elections hit an all-time high of 74 percent. That broke the previous record of 66 percent, set in 2012, which broke the previous record of 62 percent in 2008. Which broke the previous 20th century record of 52 percent in 1948, when Harry Truman won what would have been FDR’s fifth term.

Before that, you’d have to go back to both the elections of 1888 and 1892, when 55 percent of states supported the same party for president for the fifth consecutive year, during the highly polarized Reconstruction era.

The 13 states that have voted for both Republican and Democratic presidential candidates since 2000 (the past five elections) include the familiar swing states: Colorado, Florida, Indiana, Iowa, Michigan, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia, and Wisconsin. Maybe one or two new states will come into play in 2020 (most likely Arizona and Georgia), but other states on this list are now moving out of two-party competitiveness.

Yet while most states are now effectively one-party states for five elections running, the last five elections have been among the most consistently close five elections in US history. You have to go back to the period 1876 to 1892 to find a similarly close series of five consecutive elections.

Again, this is something very unusual: consistently hyper-competitive national presidential elections.

Looking back on the history of American presidential elections, it’s remarkable how many landslides there have been, since it’s been so long since we’ve had one.

More than one-third (34 percent) of our national elections since 1868 have been decided by at least 10 points. Yet, we have now had eight straight elections (32 years) in a row without a 10-point margin of victory. This is the longest streak in presidential election history, beating the previous record of seven straight close elections from 1876 to 1900 (before Teddy Roosevelt’s 1904 landslide).

These are both unusual patterns — consistently noncompetitive states and consistently competitive national presidential elections.

Their juxtaposition is even more unusual.

One way to measure this unusual juxtaposition of closely contested national elections and landslide state-level elections is to subtract the national margin from the median state-level presidential margin. When the gap is wide, it reflects the fact that national elections are much closer than state-level elections.

Again, the current period stands out as unique. In 2016, the median state-level margin of victory was 16.25 points, whereas the national margin of victory (for Hillary Clinton, who won the popular vote) was 2.1, for a record-setting difference of 14.15, eclipsing the previous record of 1896, a 13-point difference between the median state-level margin of 1896 and a national margin of victory (for William McKinley over William Jennings Bryan) of 4.3 points.

I measure the difference between the two margins, because landslide elections tend to produce landslide state-level results. The clear correlation between national and state-level margins is represented in the chart below.

But there are some patterns here.

First, let me direct your attention to the upper-right-hand quadrant, which houses the major landslide elections (more than 15-point margin). In all these years, the landslide generally sweeps the country, and very few states are close.

Then there is the lower-left-hand quadrant, in which elections are close at the national level, and states are generally competitive.

Note in the far lower-left corner lie the elections of 1960 and 1976, in which almost every state was two-party competitive, and the national margin was razor-close. It seems remarkable to remember that in the not-so distant past, there really was a time in which both parties competed almost everywhere in the country, as truly moderate broad national coalitions.

And then there are two clusters of elections in upper-left quadrant that stand out for their unusual nature — close at the national level, but not close at the state level. The past three elections (2008, 2012, and 2016) and the elections of 1896, 1900, and 1908.

This is not the common pattern in American politics.

Can we return to a more normal pattern?

The obvious question is: Will this unusual pattern continue?

After the 1896 to 1908 period, the pattern did break, and polarization subsequently began to decline.

Note that in 1912, a Republican coalition increasingly divided between its stalwart and progressive wings split, with progressive Teddy Roosevelt running as a third-party candidate to challenge incumbent Republican William Taft after Roosevelt failed to win over the Republican National Convention.

Certainly, there are some potential similarities. Now, as then, there is a growing faction within the Republican Party that is dissatisfied with the incumbent president, who they feel took their party away from them. Perhaps that faction will grow big enough to mount a TR-like kamikaze presidential challenge (I nominate Mitt Romney). This then could then destabilize the party system and initiate a scramble for new alignments, as happened in 1912.

But whereas the progressive movement of the early 20th century effectively cut across the two parties, there is no obvious analog today that effectively cross-cuts the two parties. Also note that the election of 1904 marked a tremendous landslide for Teddy Roosevelt, indicating more fluidity in the two-party system.

While it’s impossible to predict the future, one thing seems clear. The current pattern of the party system — both highly competitive at the national level, and highly uncompetitive at the state level, is very unusual.

A two-party system can work when both parties are moderate, centrist parties that appeal to the entire country. It can’t work when the parties are regional parties who appeal to very different parts of the country, which effectively divides politics along cultural and identity lines. That’s what’s happening now.

Maybe something will give, and American politics will get the major realignment our party system needs. But our political institutions right now make it very difficult. They are simply not set up to handle our current political divisions. And they are breaking under the strain.