The forthcoming article “Durable majority gerrymanders: Where partisan gerrymandering can displace democracy” by Maxwell Palmer and Benjamin Schneer is summarized by the author(s) below.
A defining feature of democracy is that the party in power should have some chance of losing it. Yet, partisan gerrymandering can enable politicians to draw electoral maps so skewed as to subvert this basic principle. In our new research, we examine “durable majority gerrymanders”—district maps specifically designed to lock in legislative control regardless of how voters actually vote.
We focus on state legislative elections, which merit particular attention for two reasons. First, in many states the legislature itself controls the redistricting process, creating a troubling conflict of interest: the same officials who benefit from gerrymandered maps are the ones drawing them. Second, because majority control of a state legislature depends entirely on outcomes within that state, a well-executed gerrymander can entrench a party’s power for a decade or more—unlike congressional elections, where national control depends on results aggregated across all fifty states.
To understand the extent of this threat, we used computer simulations to identify the most extreme maps possible for each state legislature. Our findings were stark: unconstrained gerrymandering could allow at least one party in every state to draw maps ensuring a high probability of maintaining a legislative majority for an entire decade—even when facing significant electoral headwinds. In competitive states, the effects are especially pronounced. In Arizona, Georgia, Michigan, North Carolina, and Texas, either party could potentially lock in durable majorities if given control of the redistricting process. On average, optimal gerrymandering can boost a party’s chances of winning a legislative majority by more than 20 percentage points compared to a neutral map, and in some states this advantage is even larger, as illustrated in the Figure below.
Fortunately, most enacted maps don’t approach these extremes. State-level rules—particularly compactness requirements and independent redistricting commissions—appear to meaningfully constrain the worst outcomes. Texas, however, stands out as a state where the enacted maps come closest to the theoretical limits of partisan advantage.
Why does this matter? When gerrymandering forecloses any realistic chance for the opposing party to win power, it threatens a foundational democratic principle. Legislators insulated from electoral consequences face less pressure to respond to voters, and unpopular policies can persist without accountability. As legal constraints on gerrymandering continue to evolve, understanding the outer bounds of what’s possible helps identify where reforms are most urgently needed. Our research provides that roadmap.
About the Author(s): Maxwell Palmer is an Associate Professor in the Department of Political Science, a Civic Tech Fellow in the Faculty of Computing & Data Sciences, and a Faculty Fellow at the Initiative on Cities and Benjamin Schneer is an Associate Professor of Public Policy at the Harvard Kennedy School. Their research “Durable majority gerrymanders: Where partisan gerrymandering can displace democracy” is now available in Early View and will appear in a forthcoming issue of the American Journal of Political Science.
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