Nine years ago, two Republican senators, David Vitter, of Louisiana, and Robert Bennett, of Utah, tried to introduce a measure to change the way that the federal government conducts the census. The Census Bureau tabulates the over-all population, not just that of citizens, and its results have far-reaching consequences, affecting the allocation of federal resources and the apportionment of congressional seats. The senators wanted a law requiring that respondents be asked whether they are American citizens, so that congressional districts could be redrawn. Without such a change, Vitter said, “States that have large populations of illegals would be rewarded.” Other states, like his own, he said, were being “penalized.” The subtext was that the Democrats, who tend to be prominent in areas with high concentrations of immigrants, were gaining an advantage. The measure fell short of the necessary votes, as it did when Vitter proposed it again, in 2014 and in 2016. But his efforts reflected a persistent partisan logic. Now, on the eve of the 2020 census, it has reëmerged.