From a new research paper in PS: Political Science & Politics:
“Many reformers continue to argue for a de-politicization of the redistricting process, claiming that partisan redistricting is responsible for declining electoral competition and increasing legislative polarization. Our analysis of evidence from state legislatures during the last decade suggests that the effects of partisan redistricting on competition and polarization are small, considerably more nuanced than reformers would suggest, and overwhelmed by other aspects of the political environment.”