Thomas B. Hofeller achieved near-mythic status in the Republican Party as the Michelangelo of gerrymandering, the architect of partisan political maps that cemented the party’s dominance across the country. But after he died last summer, his estranged daughter discovered hard drives in her father’s home that revealed something else: Mr. Hofeller had played a crucial role in the Trump administration’s decision to add a citizenship question to the 2020 census. Files on those drives showed that he wrote a study in 2015 concluding that adding a citizenship question to the census would allow Republicans to draft even more extreme gerrymandered...
