Thomas B. Hofeller was known in political circles as a master of drawing political districts and using demographic data to further the aims of Republicans. But before his death a year ago, the public record of his work was limited to gerrymandered political maps in North Carolina and a handful of other states, and a sheaf of expert-witness depositions in lawsuits.

That only skims the surface of his political work over the last decade.

Tens of thousands of maps and documents, kept on computer backups that were uncovered after Mr. Hofeller’s death in August 2018, show his work on a broad range of projects nationwide, from drawing political maps that maximized Republican representation during the 2011 redistricting cycle to a host of smaller projects to advance the party’s fortunes.

He kept at it to the end, promising to “bedevil the Democrats” with Republican-friendly voting districts shortly after receiving a likely fatal medical diagnosis in 2016.

The few documents made public from his work have loomed large in two major lawsuits. A legal analysis found in his files appeared verbatim in a draft proposal to add a citizenship question to the 2020 census, pointing to his personal involvement in a plan that most experts have concluded was intended to skew the census process toward Republicans. And a North Carolina state court cited data from the backups last week in striking down partisan gerrymanders in State House and Senate maps that Mr. Hofeller had drawn.