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Expert Brief

The Curious Case of North Carolina’s Congressional Map

Who draws the maps seems to drive partisan bias in North Carolina’s congressional maps more so than political geography.

Published: August 24, 2017

It some­times gets argued that geographic clus­ter­ing of Demo­crats in cities is respons­ible for the fact that Repub­lic­ans have an advant­age when it comes time to draw congres­sional and legis­lat­ive maps. That argu­ment certainly has been made in North Caro­lina, where the state has been mired in a decade long fight over alleg­a­tions of racial and now partisan gerry­man­der­ing.

But the claim that clus­ter­ing rather than polit­ics is giving North Caro­lina a Repub­lican tilt turns out to rest on some pretty dubi­ous premises. That’s because the high rate of partisan bias seen in this decade’s North Caro­lina map is a new phenomenon. And it coin­cides not with any sudden and unex­pec­ted migra­tion of Demo­crats into cities after 2010 but rather with a change in the party that had control of the redis­trict­ing process. Up until 2011, Repub­lic­ans in North Caro­lina had never had sole control of the redis­trict­ing process. That changed in 2011, and the differ­ence between North Caro­lin­a’s pre-2011 maps and the one drawn by the new Repub­lican major­ity could not be more stark.

In short, if you are look­ing for why maps in North Caro­lina and six other single-party controlled states are biased, start with who drew the map.