De-polarization of the House of Representatives?

In updating some graphs today, I discovered something interesting (but not entirely unexpected). The House of Representatives appears to be de-polarizing.

Why? COVID-19 stimulus bills, “ends-against-the-middle” voting (one, two), something else?

Of course, it’s also possible that this is just a blip.

The graphs begin in 1856-7, which is the first session with both Republicans and Democrats in the House (data). Here is the usual plot, based on distances between the party medians:

And here is another with distances between the party means:

Thanks to Dr. Jennie Sweet-Cushman for the prod.

The urban PR “spells” chart, updated

If you are reading this, you know that 24 U.S. cities tried the STV form of proportional representation. Here is an updated chart summarizing those episodes.

spells_25aug2015

The changes include:

1) Cropping to 1965, since events thereafter are basically chartjunk.

2) Adding a failed 1959 repeal attempt for Worcester, MA.

3) Changing the dates for Oak Ridge, TN, which evidence suggests to have emerged with STV a decade later than I thought. Note that the Oak Ridge council was “advisory,” whatever that means.

4) Adding Norris, TN, which I had not included because I could not find the dates of any STV elections. This Town Council was also “advisory.” Elections were held annually from 1937 through 1945. I cannot find evidence of an STV election post-1945. The federal government sold Norris to a developer in 1948, and Tennessee granted Norris its own charter in 1949.

5) Date-stamping, since this chart may evolve gain.

Please share any suggested, further changes. Wouldn’t it be nice if our state and local politics were better documented?