On his 1,062nd day in office, President Trump was impeached by the House of Representatives.

Trump faced two articles of impeachment, one focused on abuse of power and the other on obstruction of Congress. The first passed with 230 votes and the latter with 229 — more votes than were cast for either of the two articles on which Bill Clinton was impeached in 1998 (and far more than the votes from a smaller House to impeach Andrew Johnson 150 years ago).

What supporters of the president will be quick to note, however, is that almost every one of those votes came from Democrats. Not a single Republican joined the vote to impeach, although Rep. Justin Amash (Mich.) supported impeachment after becoming an independent in July following his outspoken criticism of Trump.

In the past, we’ve looked at the composition of the House as a function of how partisan each member’s district is and how ideological each member is personally. Looking at Wednesday’s vote on those axes, this isn’t particularly revelatory.

The two Democratic “no” votes joining the 195 Republicans can be seen at the upper right of the cluster of Democratic members. Amash is visible within the pool of red, below, closer to the middle. (That means he’s closer to a more moderate ideology, according to Voteview, and closer to a more centrist district by definition of the Cook Political Report.)

We can isolate those three representatives who bucked their party — or, in the case of Amash, former party. Rep. Jeff Van Drew (D-N.J.), meanwhile, voted in line with his future party: He is expected to join Republican ranks sometime soon. The other Democrat to vote with the Republicans was Rep. Collin C. Peterson (D-Minn.). He’s interesting for another, historic reason, which we’ll get to later.

Four members of the House voted neither for nor against the first article. Three simply didn’t vote, and a fourth, Rep. Tulsi Gabbard (D-Hawaii), voted “present.” Gabbard’s politics, already eccentric, have become somewhat less predictable as she’s sought the Democratic presidential nomination.

The vote on the second article was much the same, with one exception: Rep. Jared Golden (D-Maine) joined Van Drew and Peterson in opposing the measure.

Golden, like Peterson and Van Drew, is a more moderate representative from a more centrist district. That, right there, helps us see why these three were tempted to buck their party — and why more members of the House probably didn’t.

To explain, we can look at that Clinton impeachment in 1998. Although Republicans have correctly noted the extent to which the Trump vote followed partisan lines, the Clinton votes were not much better.

Clinton faced four articles of impeachment, two of which were passed by the House. The first article, which addressed charges of perjury, had the widest margin of support. All but five of the votes approving the article came from Republicans; all but six of the votes opposing it came from Democrats or Rep. Bernie Sanders (Vt.), then the chamber’s sole independent.

For the most part, those votes also reflected members of Congress who were more moderate and/or who represented districts in which the results in the preceding presidential election (Clinton’s 1996 reelection) were closer or went to the opposing party.

Not all of the votes met that standard. Most notable was Rep. Mark Edward Souder (R-Ind.), who was the only Republican to oppose the first article despite being a more-conservative-than-average representative from a solidly Republican district. He’s the red dot at upper right.

An interesting historical note: The red dot at upper left is Rep. Peter T. King (R-N.Y.), one of a few dozen legislators (55 total) to have cast votes in both Clinton’s and Trump’s impeachments. He and Peterson are the only two of that group who voted the same way — “no” on all presented articles — in 1998 and 2019.

Now the key point: Seven of the votes that bucked their parties came from members of Congress whose ideology is in a moderate zone where no current members of Congress exist.

Take away those seven votes and what do you get? Two Republicans bucking their party and one Democrat bucking his — essentially the same as what we saw in the first vote on Wednesday.

Mind you, not all of the articles in 1998 were as polarized as the vote on Article I. The fourth article, which dealt with abuse of office, was soundly defeated. Most of the opposition to that article still came from Democrats, but over one-third of the Republican caucus also rejected it.

Even then, however, the votes in opposition came from Republicans closer to the middle ideologically and electorally.

But, again, this is part of the reason the vote on Trump was so partisan: Congress is so partisan. Comparing Wednesday night’s vote with the Clinton vote almost exactly 21 years ago makes that point clear.