House 2-Dimensional W-NOMINATE Scaling
Total Number of Roll Calls: 1209
Number of Scalable Roll Calls (2.5% Minority or better): 874
Number of Constrained Roll Calls [Midpoint at end of Dimension(s)]: 84
Correct Classification:
Senate 2-Dimensional W-NOMINATE Scaling
Total Number of Roll Calls: 672
Number of Scalable Roll Calls (2.5% Minority or better): 540
Number of Constrained Roll Calls [Midpoint at end of Dimension(s)]: 72
Correct Classification:
These results show that the trends that we discuss in chapter 11 of Congress: A Political-Economic History of Roll Call Voting (1997, Oxford University Press) and Income Redistribution and the Realignment of American Politics (joint with Nolan McCarty, 1997, AEI Press) are continuing. In the post World War II period only two dimensions are required to account for the great bulk of roll call voting. The primary dimension is the liberal-conservative dimension so familiar to students of politics and epitomized by voting on the basic issue of the role of government in the economy. The second dimension captures the conflict over race and civil rights. However, with the passage of the 1964 Civil Rights Act, the 1965 Voting Rights Act, and the 1967 Open Housing Act, this second dimension has slowly declined in importance. Race related issues – affirmative action, welfare, Medicaid, subsidized housing, etc. – are now questions of redistribution. Voting on race related issues now largely takes place along the liberal-conservative dimension and the old split in the Democratic party between North and South has largely disappeared. Consequently, since the mid-1970s, American politics has become increasingly polarized around a left-right conflict along party lines.