SENATE APPORTIONMENT - COMPETITIVENESS AND PARTISAN ADVANTAGE

This paper examines two unanticipated consequences of the equal repres entation of states on Senate elections-competitiveness and partisan ad vantage. Using a fixed-effects (LSDV) model that controls for importan t intervening variables to test the hypothesis that variation in state population size affects the competitiveness of Senate elections, we f ind a far stronger relationship between state population and electoral competitiveness than have previous works. In addition, Senate apporti onment has had implications for the partisan composition of the Senate . When we compare the actual outcomes of Senate elections over time wi th hypothetical outcomes, which we derive by holding state population constant, we find that Senate apportionment has had important conseque nces for the partisan composition of the Senate in several periods. Fr om the mid-1970s until (but not including) 1994, Senate apportionment enabled Republicans to hold seats disproportionate to their party's sh are of the national Senate vote.