The <http://voteview.uh.edu/c46105.htm> URL visually shows the polarization of Congressional voting over the last century. As the note below observes, the parties are far more polarized in voting patterns today than any period since the last century.
Folks can pretend there is little differece but maybe a visual demonstration will help.
Nathan Newman nathan at newman.org
----- Original Message ----- From: "Hughes, James" <James.Hughes at trincoll.edu>
>From the Authors of Income Redistribution and the Realignment of American
Politics (with Nolan McCarty, 1997, AEI Press).
<URL: <http://voteview.uh.edu/c46105.htm> >
The House is on the left, the Senate on the right
This fascinating (but rather large) animated GIF maps the voting pattern of actual US congresses, from the 46th through the 105th, with respect to their two largest axes. What do these axes represent? That's the beauty of the graph: there is no a priori ideological input. Rather, the authors tallied all actual votes of each congress, and by factor analysis picked out the "long axes" of the ellipsoid---the vector sum of votes that most strongly distinguished the actual voting senators and congressmen from one another.
It turns out that there is one strongly dominant axis at all times in the century-plus under study. Of course, this axis is what we think of as "left vs. right", but what it _means_ will vary (smoothly and adiabatically, it turns out) over time. Being "left" may mean low tariffs and free silver in the time of WJ Bryan and just the opposite in the time of Tip O'Neill, but at all times it means voting most of the time with others who cluster together most of the time, and who differ with their opponents more on that axis than on any other. The second-biggest axis, representing the strongest political alignment perpendicular to "left vs. right" on the American political scene, is about a third as big as the left-right one, and is here represented as up-down. No other axis is anywhere near as big as these two, so a 2-dimensional map truly is a faithful visualization of what US politics is about---not because some pundit says so, but because the statistics of actual congressional votes say so. The secondary axis can be variously described depending on the era: in the late nineteenth century it amounts to Yankee/black against Southern/Catholic, while by the mid-twentieth it is mostly about segregation (even though, again, the votes that define it may have nothing obvious to do with that issue). In recent decades the secondary axis has a strong "family values" component, but the distribution of votes says it's still "the same" axis as it was fifty or a hundred years ago.
A few minutes of observation of this mesmerizing map will tell you more about the shape of American politics than most college textbooks. A few salient features that jump out at me:
(1) The two parties are REAL. The overlap grew smaller from 1900 to 1980, and in the Vietnam era there were dozens of congressmen and several senators whose party affiliation could not be reliably determined from their voting patterns. Since then the gap has rapidly widened again, and since 1994 the two parties have been as polarized as they were in the McKinley era.
(2) The Progressive party, which started the 20c at the top of the chart, slid to the bottom as the vertical axis morphed from farm support to civil rights. They were never as far left as the extreme left of the Demo party; their existence was mostly about this second axis.
(3) The most dramatic anecdotal feature of mid-20c US politics, the Dixiecrat split of the Democratic party, is also spectacularly real; by 1964, the southern Demos are so far up and to the right that they have less overlap with northern Demos and Republicans than those two have with each other. The US went through a true tripartisan era without ever changing the colors on the bunting.
(4) Since 1980, the Republican party has reached up and grabbed the Dixiecrat pseudopod hanging above (and not to the left) of it. There are no longer any "Weicker Republicans" (below all Demos and to the left of many of them) and even "Jeffords Republicans" (below all Demos, full stop) are getting thin on the ground. The bipartisan axis had tilted by 1994 to nearly straight left-vs.-right, and by 2000 (not shown here) it has begun to turn further, giving the Republicans a bias toward voting patterns that evolved out of the segregationist camp. However, the parties remain "mostly" about left-right (again, whatever that means to each cohort) and the gap between them is wider than it has been since about WWI.
So anyway, here's the URL. Let me know if you notice anything striking.
<URL: <http://voteview.uh.edu/c46105.htm> >
----------------------------------------------- James J. Hughes Ph.D. Associate Director of Institutional Research and Planning Trinity College 71 Vernon St., Hartford CT 06106 860-297-2376, james.hughes at trincoll.edu