By the standard of most European parliaments, levels of party voting in the United States Congress are relatively low. Nevertheless, party voting does occur in the House of Representatives and the Senate. In the American context, a party vote occurs when majorities of the two congressional parties, the Democrats and the Republicans, oppose one another. The authors construct measurements of levels of party voting in Congress in the years after the Second World War. They then develop a model to test the effects of a number of independent variables that influence fluctuations in party voting levels over time. The study models the time series for party voting and demonstrates striking differences between the House and Senate in the correlates of partisan cleavage.
* Department of Political Science, Ohio State University, Columbus, Ohio. When we assembled and initially analysed these data, Patterson was a John Simon Guggenheim Memorial Foundation Fellow. The data were gathered during a year of hospitality extended by The Brookings Institution, Washington, DC, where Patterson served as a Visiting Fellow. Patterson received research support from the Everett McKinley Dirksen Congressional Leadership Research Center, Pekin, Illinois. Caldeira benefited from a University of Iowa Faculty Scholarship. We are grateful for the research assistance of Brad Lockerbie, University of Iowa. For prudent technical advice, we appreciate the help of John R. Wright, University of Iowa. And, for help with various facets of computing, we thank Chia-Hsing Lu, Systems Programmer, University of Iowa Laboratory for Political Research.