The Marginals Never Vanished: Incumbency and Competition in Elections to the U.S. House of Representatives, 1952-82

The average vote margin enjoyed by incumbent candidates for the U.S. House of Representatives increased sharply during the 1 960s. Despite this, and contrary to assumptions common in the literature on recent congressional elections, electoral data show that House incumbents are no safer now than they were in the 1950s, the marginals, properly defined, have not vanished; the swing ratio has diminished little, if at all; and competition for House seats held by incumbents has not declined. Vote margins increased without adding to incumbent security, diminishing competition, or dampening swings because the heterogeneity of interelection vote swings increased at the same time.