North Carolina’s congressional and state House districts are among the most Republican-skewed in the country despite voter preferences that are relatively evenly split, according to an Associated Press analysis. The AP calculated the partisan advantage for North Carolina Republicans in the 2016 state and federal House races through a new statistical tool that’s designed to detect cases in which a political party maintained or increased its grip on power through how it drew voting districts. The measurement, known as the “efficiency gap,” has separately gained attention as a key argument in a pending Supreme Court case from Wisconsin that alleges partisan gerrymandering. It’s also cited by groups challenging the design of North Carolina’s congressional map, though the Republican defendants argue the measure shouldn’t be used as a legal standard. In the nationwide AP analysis, North Carolina had the highest efficiency gap – or greatest Republican advantage – among the roughly two-dozen largest states that determine the vast majority of Congress.
An attorney leading one of the challenges against North Carolina’s congressional map, Anita Earls, described the efficiency gap in an interview as “an easily applied and really easily understood measure for how much partisanship is too much.”
“While I think it is possible to minimize the issue of partisanship, it’s also true that inevitably if you have legislators drawing the map there will be some partisan consideration,” said Earls, the executive director of the Southern Coalition for Social Justice. But the efficiency gap, she says, uses “data to make sure the districts are within a normal range of fairness.”
However, an expert witness for the Republicans sued by Earls’ group, political scholar and journalist Sean Trende, cast doubt on whether the efficiency gap can serve as a single measure for judging elections around the country.
“Gerrymandering has no particular hallmark; it is inherently a fact-intensive inquiry,” Trende wrote in an April report for the North Carolina case. “This is especially true if we are going to measure it in terms of elections, which are frequently beset by unpredictable effects that have long-lasting consequences.”