From Ezra Klein of Vox.com ("Everything you need to know in two minutes, using two brain cells") comes an analytically-challenged piece with an awkward title:
A stunning graph on how money polarizes politics
Now, I suppose that what young Ezra is getting at is that there is a large moderate slice of the population that doesn't donate much money to political causes (as shown in the graph on the left), so that the extreme believers (especially the donors of more than $200) on both the Left and the Right ends of the spectrum dominate the discussion. That's the banal, self-evident point that Ezra thinks his "graph is on."
Unwittingly, though, Ezra has provided us with an insight.
Upon first sight of the graph of large donors (enlarged below), what I found to be noteworthy was its lack of symmetry.
Now, I'm not certain what that horizontal axis represents, but let's take it at face value that it is a measure of political extremism, zero being neutral, -15 "Very Liberal" and +15 "Very Conservative". So says Ezra.
So how polarized are the Liberal and Conservative donors? To make that dimension easy to visualize, I merely took the mirror image (absolute value for you math majors) of the Liberal side of the spectrum, shaded it yellow, and plotted it on the positive scale, so that 15 represents "extreme" for both Liberal and Conservative. The resulting graph is below:
OK, so here's my analysis. Close to half the Liberal large donors score above 10 points, compared to 10 to 12% of the Conservative side of the spectrum. (I don't have benefit of the underlying data so all values are estimates.) The typical (median) Conservative large donor would appear to be 5 points or more less extreme than the Liberal counterpart.
This fits with the analysis that America is a center-right nation. There are lots of large donors on the Right, but most are not political extremists, as much as Ezra Klein and his Juicevoxers would like to represent them (us) as dangerous and radical.
On the other hand, the Big Money "Progressive" donors (think Soros, Steyer and hard-Left Berkeley radicals) are extreme. The tallest Progressive bar accounts for over 10% of the money represents ideas that are more extreme than those of all but the very most Conservative donors.
My sense for quite some time is that the power and the push (and the President) of the Democratic Party represents thought that is to the Left of 85% of the American people. These graphs pretty much confirm that, and it should be no surprise. Yes, Ezra, these graphs explain much about our polarization, but I don't think the answer is the one you wanted.