The Effect of Majority-Minority Mandates on Partisan Gerrymandering

I develop a model of optimal partisan gerrymandering to analyze the claim that majority-minority legislative districting helps Republicans. I first determine the number of Democrats elected in states where Democrats control redistricting and the number of Republicans elected in states where Republicans control redistricting. I then determine how electoral outcomes change if the federal government requires redistricters to create majority-minority districts. In states where Republicans control redistricting, majority-minority mandates weakly decrease the number of Republicans elected. In states where Democrats control redistricting, a bare majority-minority mandate does not affect the number of Democrats elected. However, if Democratic redistricters face geographical constraints or supermajority-minority mandates, some Democratic votes are wasted and the number of Democrats elected weakly decreases.