The Marginals Never Vanished?

In a recent article Gary Jacobson concludes that “House incumbents are no safer now than they were in a the 1950s; the marginals, properly defined, have not vanished; the swing ratio has diminshed little, if at all; and competition for House seats held by incumbents has not declined.” While Jacobson propounds an extremely provocative argument, there are complicating patterns in his evidence that support addtional and/or different interpretations. On the basis of these complicating patterns we argue that the marginals, “properly defined,” have diminished, the swing ratio has declined, and party competition for House seats held by incumbents has lessened. Thus, while fears that the vanishing marginals phenonmen would lead to lower responsiveness on the part of “safe” House incumbents have proved groundless, the colelctive composition of Congress does appear to be less responsive to changes in popular sentiments.