A Cut-And-Choose Mechanism to Prevent Gerrymandering

TL;DR

This paper introduces a novel cut-and-choose mechanism for districting that ensures fair electoral outcomes without geometric constraints, by allowing one party to divide and the other to set support thresholds, leading to equitable results.

Contribution

It proposes a new end-to-end districting mechanism that guarantees fairness through strategic division and threshold setting, independent of geographic constraints.

Findings

Mechanism always yields fair outcomes in equilibrium

Supports two-party districting without geometric restrictions

Ensures fairness up to integer rounding

Abstract

This paper presents a novel mechanism to endogenously determine the fair division of a state into electoral districts in a two-party setting. No geometric constraints are imposed on voter distributions or district shapes; instead, it is assumed that any partition of the population into districts of equal population is feasible. One party divides the map, then the other party chooses a minimum threshold level of support needed to win a district. Districts in which neither party meets this threshold are awarded randomly. Despite the inherent asymmetry, the equilibria of this mechanism always yield fair outcomes, up to integer rounding.