Senate Apportionment and Partisan Advantage: A Second Look

In an earlier paper, Lee and Oppenheimer (1997) found that apportionment has generally functioned as a check on majority rule since the institution of direct Senate elections. Also, according to the authors, apportionment has consistently worked to the advantage of Republicans since 1956. Its influence, however, was more pronounced between 1980 and 1986 than in the 6-year electoral cycle ending in 1994. As a result, the authors surmise that the most recent Republican control of the Senate may outlive that of the 1980s. This analysis reconsiders the impact of apportionment on Senate elections. The findings indicate that apportionment's check on majority rule occurred less frequently than originally claimed; that apportionment's pro-Republican bias began at least two decades after its alleged onset in 1956; and that the size of apportionment bias is generally smaller than that estimated by Lee and Oppenheimer. Finally, bias did not vary significantly during the two most recent periods of Republican control of the Senate. Hence, apportionment appears irrelevant to any forecast about the endurance of the current Republican majority.