Redistricting and Competition in Congressional Elections Forces beyond gerrymandering explain rising number of districts that strongly favor one party by Alan I. Abramowitz
KEY POINTS FROM THIS ARTICLE
-- Based on presidential voting patterns, a much larger proportion of U.S. House districts strongly favor one party and a much smaller proportion are closely divided than 50 years ago.
-- However, gerrymandering is not the major reason for this trend. Partisan polarization has increased dramatically in U.S. states and counties, whose boundaries have not changed.
-- Moreover, despite the growing partisan divide evident in presidential voting, the competitiveness of House elections has changed very little over the past 5 decades because the personal advantage of incumbency has declined sharply during this period.