Some politicians claim that including undocumented migrants in the census unfairly benefits Democratic-leaning states by giving them more congressional representation. But new research suggests this concern is overstated.

A study from the University of Minnesota examined census data from 1980 to 2020, using state-level estimates of the undocumented population at each point. The researchers calculated how congressional apportionment and Electoral College votes would have changed had these residents been excluded. Unlike previous analyses, which relied on projections and focused only on the 2020 census, this study used actual historical data to assess long-term trends.

Little impact

The findings show that excluding undocumented migrants would have had little effect. In no census year would more than five House seats or Electoral College votes have shifted. And in no case would the balance of power in the House or the outcome of a presidential election have changed. While some states might have gained or lost seats, the overall impact on national politics would have been minor.

In short, removing undocumented migrants from the census would have had almost no effect on past elections and is unlikely to matter much in the future.