The Vanishing Marginals, 1824-1980

Recent research on House elections has focused on the decline in marginal districts since the mid-1960s. However, this body of research suffers from two major problems: (1) its exclusive reliance on a limited time frame which calls into question the generalizability and adequacy of its explanations; and (2) its overemphasis on incumbency-oriented explanations. Using aggregate electoral data to examine trends in electoral safety from 1824 to 1980, we find that recent safe-seat percentages are consistent with a long-term trend beginning in 1932, and consistent with an even longer-term upward trend beginning in 1896. Further, although incumbent winners increased their electoral advantage over nonincumbent winners in the post-1896 period, this trend leveled off in the mid-1960s. As such, it appears that the post-1965 increase in electoral safety is a winners', and not an incumbency, advantage. Such findings cast doubt on the adequacy of explanations which focus on post-1965, incumbency-oriented factors.