Constituency Congruency and Candidate Competition in Primary Elections for the U.S. House

Previous research has largely concluded that House elections have become less competitive in the modern era. Our research examines one area where we expect to observe more competition-namely, primary elections. In this article, we investigate when and where a state legislator will emerge to run in a congressional primary. All else equal, we expect that state legislators who can carry a large portion of their old state reelection constituency to the "geographic" congressional constituency will be more likely to emerge and receive a higher vote share in the election. Using geographic information systems (GIS) techniques, we are able to derive a measure of constituency congruency by focusing on the degree of intersection between state legislative and congressional districts. Our results indicate that state legislators are more likely to emerge in a primary if constituency congruency is high, especially in open seat contests. Congruency does not appear to provide an electoral advantage at the polls.