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Democracy’s Denominator: How Citizenship-based Redistricting Impacts Racial Minority Voters

The project: For the past half century, congressional and state legislative districts in the U.S. have been drawn to equalize the total population of each district. However, legislators in several states with Republican-controlled legislatures have hinted at potentially changing the unit of apportionment to eligible citizen voters, and the Trump administration took steps to facilitate that switch. Under this new approach, called citizen voting-age population (CVAP) equalization, legislative and congressional districts would be designed to equalize the number of adult citizens, rather than total population. This project ran simulations for 10 states to determine how equalizing voting districts based on CVAP would impact minority representation and partisan preference.

The process: Researchers used randomized redistricting to create two sets of legislative district maps that illustrate what would happen if districts’ CVAPs rather than their total populations were equalized. Researchers focused on 10 states with below-average ratios of CVAP to total population (signifying relatively large populations of non-citizens and residents who are not of voting age). These states — Arizona, California, Georgia, Idaho, Illinois, Nevada, Florida, New York, Texas, and Utah  — are the places where switching from equal-total-population to equal-CVAP districts could make the biggest difference.

Results: The redistricting simulations found minority representation would likely decline significantly in Arizona, Florida, New York, and Texas. If these states changed their unit of apportionment from total population to CVAP, their shares of minority opportunity districts could be expected to fall by six or more percentage points. On the other hand, the partisan impact of a different apportionment base would probably be more muted. Overall, Republicans would win more seats in redistricting plans that equalized districts’ CVAPs — but only slightly more seats, generally not enough to disturb the partisan balance of power. This conclusion holds, moreover, whether districts are drawn by a nonpartisan mapmaker or a gerrymanderer and whether one or many electoral environments are analyzed.

Jowei Chen, associate professor, Department of Political Science, University of Michigan