The effect of majority-minority mandates on partisan gerrymandering

I develop a model of optimal partisan gerrymandering to analyze the claim t hat majority-minority legislative districting helps Republicans. I first de termine the number of Democrats elected in states where Democrats control d istricting and the number Republicans elected in states where Republicans c ontrol redistricting determine how electoral outcomes change if the federal government requires redistricters to create majority-minority districts. I n where Republicans control redistricting, majority-minority mandates weakl y decrease the number of Republicans elected. In states where Democrats con trol redistricting, a majority-minority mandate does number of Democrats Ho wever, if Democratic redistricters face geographical constraints or superma jority-minority mandates, some Democratic votes are wasted and the number o f Democrats elected weakly decreases.