During the Senate's debate on a government funding measure, Senator Tom Harkin of Iowa analogized the current tension on Capitol Hill to the period around the Civil War. And in at least one sense — polarization — he has a point.

That really wasn't what Harkin was getting at. As reported by our colleagues at the National Journal, the senator was suggesting that the strategy from his conservative Republican colleagues was intended to both excite the conservative base and simultaneously suppress voters dispirited by the tension in Congress. He continued: "It's very dangerous. I believe … we are at one of the most dangerous points in our history right now. Every bit as dangerous as the break-up of the Union before the Civil War."

We've noted the work of VoteView previously. A project of Keith Poole, a professor of political science at the University of Georgia, the site measures, among other things, political polarization by looking at how often members of Congress deviate from their party on roll-call votes. Earlier this month, the site updated its polarization data to include votes taken so far in the 113th (current) Congress.

[W]e find that polarization ticked upwards from 1.09 in the 112th House to 1.11 in the 113th House. This increase is entirely attributable to a change in the House Republican mean from 0.69 to 0.71 on the liberal-conservative dimension.

In fact, the Republican Party in the House is more polarized now than at any point since VoteView's data begins, in 1879 — 14 years after the end of the Civil War. But it's when contrasted to the polarization of Democrats that the divide becomes more obvious. Below, we've combined VoteView's graph tracking the difference in polarization between the two parties — the gap between where each party lies on the liberal-conservative spectrum — over the past 134 years to highlight the point. The black line is the polarization in the House; the red is the Senate.

In both chambers, polarization is higher than at any point in the project's data. In 1879, each was around 0.8 in VoteView's metric. Now the Senate is around 0.9, and the House is above 1.1.

Again, Harkin's point was a tactical one, that his opponents wanted to foster fractious politics for their own electoral gain. But his analogy was more correct than he may have intended: politics is already fractured, largely because of the Republican party's shift right, and moreso than at any point since the administration of Civil-War-general-turned-president Ulysses Grant.

Update, 1:10 p.m.: At The Atlantic, James Fallows makes a related point.

Photo: Composite of a Civil War battlefield with the Senate leaders from each party. (AP)