It seems like only a week ago that we declared this to be the golden age of partisanship, which is because it was a week ago that we made that declaration. There were a number of factors to which we pointed, including the increasing gap in presidential approval ratings between members of the president's party and those of the opposing party. That gap hit a new high in 2016.

But of course the benchmark for how split our politics have become has been and continues to be the partisanship displayed by Congress.

The Voteview project has measured the partisanship of members of Congress back to the country's inception. Key votes are analyzed on the spectrum of how much or little government involvement there is in the economy, allowing a measure of how liberal (more involvement) or conservative (less) the vote and voter are.

With the 114th Congress wrapping up its work, Voteview summarizes the past two years: “The most polarized Congress since the early 20th Century.”

Why? Because the membership of the House and Senate in both parties has shifted to the poles of partisanship, leaving the middle all but vacant. This graph makes the point:

The lighter lines are the House and the darker lines the Senate. There's little action at the middle of the spectrum and two hills in the center of the “liberal” and “conservative” measure — with the House's hills peaking slightly more to the extremes than the Senate's.

We can extend this backward. There have been moments of stark polarization before, but the recent trend is dramatic. The colors on the chart below track liberal or conservative views of members of Congress, not party identification. The height of the bar is how many members of each chamber fall at that point on the spectrum.

You can use the arrows to toggle through the last few Congresses. Notice how the middle has grown emptier — which is in part a function of more moderate candidates losing elections, often in the primaries.

We can view this another way. Since 1901, here's the percentage of all of the members of each chamber who have scored in the middle, the -0.15 to 0.15 range.

It's perfectly possible that the real golden age of partisanship was at the turn of the last century, before we had robust polling on presidential approval (among other things). But this is, at least, a golden age of partisanship, and the Congress that just moseyed into the sunset set a new high-water mark.

We're confident that the next Congress has a good shot at surpassing it.