Partisan Voting Patterns in the U. S. Senate, 1877-1986

In this paper we describe patterns of party voting, party cohesion and party strength in the U.S. Senate from 1877 through 1986, and replicate, for the Senate, earlier explanatory models developed for the House of Representatives. We then refine and extend these models to correct for autocorrelation and measurement problems in the replicated analysis. The new analysis demonstrates that cohesion and strength for the two parties in the Senate are driven by different forces. For Democrats, cohesion and strength have been a function of the size of the Southern Democratic contingent. For Republicans, cohesion and strength are a product of membership turnover and presidential partisanship. Finally, we note the close correspondence between the overall patterns of party voting in the Senate and the House and discuss potential causes and implications of this relationship.