When Stephanie Hofeller visited her mother a few weeks later, the daughter found that the sweep of her father’s work documents had been woefully incomplete. Still in the apartment were four external hard drives and 18 thumb drives containing some 75,000 documents generated by her gerrymandering father.

Two weeks ago, Hofeller’s overlooked cache of redistricting documents made their debut in a federal court filing, part of an attempt by the American Civil Liberties Union to block the Trump administration’s plan to include a U.S. citizenship question in the constitutionally required 2020 census. A decision by the U.S. Supreme Court is expected by the end of this month.

Opponents have said including the question, last used in 1950, would lead to undercounts of minority populations. Commerce Secretary Wilbur Ross has said the question is necessary to enforce the Voting Rights Act — an explanation that has drawn nothing but smirks from Democrats.

A memo written by Hofeller before he died, and introduced as evidence in late May, offers a more compelling reason for the citizenship question.

I will let Emmet Bondurant explain.

Bondurant is an Atlanta attorney whose defense of voting rights stretches back to the 1960s. He currently sits on the national governing board of Common Cause and is the lead counsel in a challenge to North Carolina's congressional district map.

That case was argued before the U.S. Supreme Court in March. North Carolina’s GOP-controlled state Legislature drew the congressional map with the expressed intent of producing as many Republican members of Congress as possible.

And so a state that is split 50-50 between Republican and Democratic voters elected 10 GOP candidates to Congress in 2018 and only three Democrats. Hofeller drew that map for the North Carolina Legislature. Bondurant deposed him.

There’s no need to go further into the North Carolina case — which the high court is also expected to decide later this month. Suffice it to say that Bondurant was familiar with Hofeller and was one of a tight circle of Common Cause lawyers who soon learned of the trove of documents the Republican map designer had left behind.

Shift your attention instead to Texas.

In 2015, a pair of voters there challenged a state Senate map drawn by a panel of federal judges — after the jurists had found a previous map unconstitutional. This map, too, was illegitimate, claimed plaintiffs Sue Evenwel and Edward Pfenniger, because the judges had used Texas’ total population to draw the state Senate districts rather than registered voter population. (Texas has a substantial noncitizen population.)

The U.S. Supreme Court upheld the Texas maps in 2016, but two conservative jurists, Clarence Thomas and Samuel Alito, noted that Texas wasn’t obliged to use a state’s total population to apportion its legislative districts. Other means could be used, they said.

Enter Hofeller. His calculations indicated that if states drew political boundaries according to the number of U.S. citizens in each district, parties that depended on non-Hispanic white voters would benefit.

But he needed more data to be sure. Hence the citizenship question on the U.S. census. The Trump administration has called the citation of the Hofeller memo “an unfortunate last-ditch effort” to avoid a legal defeat.

Bondurant said the Hofeller memo is a glimpse of the future.

“This whole effort of putting citizenship data in the census is a political ploy to provide the factual basis for some states with Republican majorities to amend their reapportionment statutes — to try to mandate that their state legislative districts, school districts, county commission districts be apportioned not based on total population, but based on citizenship,” he said. “That’s exactly where it’s headed.”

Congressional districts wouldn’t be affected — the U.S. Constitution makes clear that total population is the standard for reapportionment, Bondurant said. States are another matter — particularly those with constitutions that don’t dictate how populations are to be tallied. Texas is one. Georgia is another.

“We don’t have a required, population-based apportionment requirement,” said state Sen. Jen Jordan, D-Atlanta, who sits on the Senate Reapportionment Committee.

Majority votes in the Legislature’s two chambers and a governor’s signature are all that would be required.

Where might apportionment according to U.S. citizenship make a difference? In counties with high immigrant populations. Think Hall and Gwinnett counties in metro Atlanta, and Whitfield County outside Chattanooga.

“It’s definitely an open question,” Jordan said.