Polarization

Erasmus at Civic Dialogues has a post comparing the ideological distribution of House representatives in the 91st Congress (69-70) to that of the 106th (99-00). In the 91st Congress, there is significant overlap between the two parties.

In contrast the 106th Congress graph's two mountains have virtually no overlap! The democratic plateau has disappeared and the republican mountain has moved farther right creating a distinct 'valley' between the mountains. It's a great illustration of how our politics has become polarized.

Now here's the problem: my understanding is that the ideology of about one third of the American electorate is right where this valley is!

What contributed to this polarization?

Here's the easiest part of the answer: Roe v. Wade. This clearly doesn't tell the whole story, but prior to that decision, conservative religious Protestants, particularly in the South, were not a very active political force. When Blackmun was writing his Roe decision, he was under the impression that it was only Catholics who would be upset at the outcome. He was obviously quite mistaken.

The post-Roe influx of the "Moral Majority" into the Republican party began the rightward drift of that party, but it wasn't until the 1990s, with the Christian Coalition (et al) and the Republican takeover of Congress that this group became dominant.

The other big shift has been on the Democratic side. While the Democratic ideology hasn't changed all that much in the last 40 years (look at Dick Gephardt), its membership has shifted. The Dixiecrats, who might have made up a chunk of that middle ground in 1969, are pretty much gone, replaced by Republicans who are also conservative on economic issues.

Those are the two contributions to polarization that immediately come to mind... I'm sure there are more.