This article investigates the influence of electoral rules on the factional systems that emerge in the primaries of a one-party political system. It shows that at the state level, especially in gubernatorial primaries, Key (1949) is correct that Southern states did not typically follow the Duvergerian logic that for single-member districts there should be two competitors in plurality-rule primaries and three or fewer competitors in majority-rule with runoff primaries. However, it is found that Southern counties and parishes did satisfy the expectations of institutionalists. The latter finding is novel and important because it would seem to imply some form of political communication or organization that structured elections at the local level.