Politicians have been redrawing districts to benefit their own political parties—a tactic known as gerrymandering—since the 1970s. But recently, technology has enabled politicians to choose their voters more strategically than ever before. In the video above, The Atlantic writer Vann R. Newkirk II explains how big data can help win elections—and why Pennsylvania and Maryland have already faced lawsuits over gerrymandering technology.

For more, read Newkirk’s article, “How Redistricting Became a Technological Arms Race.”