Watch the Republican Party gallop to the right over the last 40 years in this amazing chart

As we watch House Republicans descend into epic disorder, let us contemplate once more how we arrived at this congressional apocalypse: Republicans have run so far away from the middle of the political spectrum that a significant nihilist minority of the party now regards any compromise with Democrats as tantamount to treason.

That's what we see in the dramatic figure above: The most liberal Republicans of today occupy the same ideological space as the most conservative Republicans of the 1960s. On the left, the pink bars (known as a histogram) show the distribution of House Republicans from the late 1960s on an widely respected scale of ideological measurement known as DW-Nominate; the higher the bars, the more members of Congress who occupy that space. On the right, almost entirely separated, we have the dark red histogram for the 2013-2015 session of Congress. It didn't exactly happen overnight, but the difference is stark.

But, but, but—both sides do it, right?!

Nope. Not at all. While the Democratic caucus has indeed become more liberal on average, it has done so mainly by losing its conservative flank, not by jumping off of the left-most cliff. The graph below shows that the most liberal Democrats of the 1960s are pretty much in the same spot as the most liberal Democrats of the 2010s, and there's far more overlap between the two than there is in the Republican chart.

Put another way, if Democrats had lurched as far to the left as Republicans have to the right, Bernie Sanders would have been more conservative than almost the entire Democratic Party back when he was serving in the House.