THE DISTANCE BETWEEN THE PARTIES…. The conventional wisdom among many political observers is that Democrats and Republicans should be able to work together to find compromise solutions to pressing problems. Politicians should “put aside their differences.” Legislation should be “bipartisan.” Effective leaders should be able to “bring people together.”

It’s worth noting, from time to time, the practical and ideological problems with this approach to problem solving. The parties disagree — as they should; it’s why they exist — and are more polarized now than at any point in modern political history. Ezra has posted this chart from Nolan McCarty, Keith Poole, and Howard Rosenthal before, but I’m glad he ran it again yesterday. It shows current political polarization is at its highest point since the 19th century:

This political environment obviously makes compromises and “bipartisan” solutions very difficult, since the parties, more so than at any recent point, simply see matters of state in fundamentally different ways. But the polarization among lawmakers in both chambers also, as Ezra noted yesterday, “makes it virtually impossible to govern in a system that is designed to foil majorities and require a constant three-fifths consensus. It’s not good if the country is virtually impossible to govern. Problems don’t stop mounting while we try and figure things out.”

There’s been some talk lately about the effort to convince at least some Republicans to support health care reform, the way plenty of Republicans supported Social Security and Medicare in previous generations. In those eras, the parties were closer together, and there were center-left GOP lawmakers from across the country who were amenable to outreach.

This period, it should be noted, did not last long. Looking at the chart, we see the parties came much closer together in the wake of the Great Depression, and the polarization remained low for several decades. It created an environment in which bipartisan policymaking was considerably easier.

And that’s long gone. To reiterate a point Harold Meyerson emphasized this week: “Nationally, the [modern Republican Party] is dominated by Southern neo-Dixiecrats. In their book ‘Off Center,’ political scientists Jacob Hacker and Paul Pierson compared congressional Republicans of different eras and concluded that a Republican House member in 2003 with a voting record that placed him at the median of his party was 73 percent more conservative than the median GOP member of the early ’70s. Max Baucus, then, isn’t negotiating universal coverage with the party of Everett Dirksen, in which many members supported Medicare. He’s negotiating it with the party of Barry Goldwater, who was dead set against Medicare. It’s a fool’s errand that is creating a plan that’s a marvel of ineffectuality and self-negation — a latter-day Missouri Compromise that reconciles opposites at the cost of good policy.”

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.