Does Ranked Choice Voting Promote Legislative Bipartisanship? Using Maine as a Policy Laboratory

Abstract Political polarization in the United States has increased dramatically, hampering the functioning of American government. Some scholars attribute this dynamic to the use of plurality elections and posit that a ranked choice voting (RCV) system may promote greater bipartisanship. Maine’s 2016 adoption of RCV presents an early opportunity to test this theory on congressional races. Using comparative analysis, we show that bipartisan bill cosponsorship increased after the adoption of RCV in Maine’s swing House district but not in its safe district. These results, along with more anecdotal evidence from Alaska, which introduced RCV in 2020, indicate an association between RCV and bipartisanship. However, it is an open question which way the causation runs. On one hand, RCV has, to date, been implemented in states that have a history of and prerequisites for bipartisanship (e.g. competitive races involving both major parties and third parties/independents, and significant numbers of centrist or independent voters). On the other hand, RCV may more easily allow jurisdictions with such “preconditions” to elect centrists who are primed for legislative bipartisanship. In the next few years, there will likely be a more diverse collection of House and Senate races held under RCV, and we can better understand how the causation works.