How next-gen computer generated maps detect partisan gerrymandering
In October 2019, a state court determined that North Carolina’s congressional districts had been severely gerrymandered and struck down the state’s map. The court’s ruling was informed, in part, by tens of thousands of alternative maps demonstrating that the district boundaries had very likely been manipulated for political gain, the very definition of gerrymandering. Researchers had generated a slew of alternative, computer-generated maps designed to help identify potential patterns of bias. The approach is increasingly used, alongside other tests, to ferret out alleged gerrymandering. District manipulations can be so subtle that they’re undetectable just by looking at them. “The eyeball test is no good,” says Jonathan Katz, a political scientist and statistician at Caltech. U.S. states redraw their district lines every 10 years to adjust for changing demographics picked up by the national census. The last round a decade ago raised eyebrows, most notably for districts drawn in Michigan, North Carolina and...