For much of the last century Republican incumbents were running in districts that were not strongly inclined to support their party. The process of realignment has gradually resulted in most now running in districts more amenable to them. That, in turn, has increased their electoral security. If that is occurring, we should be able to analyze incumbent election results by party and see changes largely benefiting Republican incumbents.

PARTY, AVERAGE VOTE PERCENTAGES, AND SAFE SEATS

The most frequently used indicator of the situation of an incumbent is the average vote percentage of the incumbent. The important matter is what happens when we examine this indicator from a partisan perspective. Prior analyses have examined all incumbents together. If only contested races are examined, there is an increase. If all incumbents are included, there is no increase after 1946. Indeed, as Figure 7.1 indicates, the only sustained increase in the vote percentages of all incumbents in the last century occurred in 1918, when the average of all incumbents increased from the lower 60s to the upper 60s. It has stayed at that level, with some fluctuations, since then. It is difficult to see any significant change from 1964 to 1966 in the overall average.

This average, while interesting, prevents us from seeing any changes that are partisan in nature. Figure 7.2 separates the average percentages of the vote won by incumbents by party. The major change over time is what has happened to Republicans.