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Efficiency Gap: The Greatest Weapon to Fight Partisan Gerrymandering

by Shawn M. Griffiths, published

The fight against gerrymandering nationwide is taking a new turn. Courts are no longer just looking at discrimination based on race, sex, or class, but political discrimination and partisan motives to consolidate power and weaken the voice of voters outside the party in power.

First it was Wisconsin. Then it was Pennsylvania. Now, more states are open to legal challenges against partisan gerrymandering thanks to the "efficiency gap," the statistical method used in Whitford v. Gill to determine that Wisconsin Assembly lines were so extremely partisan that it constituted a gerrymander and violated the rights of voters outside the Republican Party.

In the simplest of terms, the "efficiency gap" compares the statewide average share of each party's vote in the districts with the statewide percentage of seats it wins. A consistently large gap between the numbers will indicate a gerrymander has occurred.

New AP analysis using the "efficiency gap" reveals just how extensive the problem of partisan gerrymandering is.

In Indiana, for instance, even though state House Republicans averaged 57.6 percent of the vote, they won 70 out of the state's 100 seats.

In Colorado, a tight battleground state, Democrats took 57 percent of state House seats despite getting just over 50 percent of the statewide vote in November.

Donald Trump took 34 percent of the vote in Maryland, yet only one of its congressional districts is represented by a Republican. This is because Democrats intentionally implemented a 7-1 plan after the 2010 census to ensure they got all, but one seat.

Pennsylvania is considered one of the biggest offenders of partisan gerrymandering, along with Maryland. A new lawsuit shows that even though Democrats made up the majority of the statewide vote in 2012, Republicans took 72 percent of the congressional districts thanks to their 2011 strategy of "cracking" and "packing."

One district is so bizarrely drawn in Pennsylvania that not only does it look like Goofy kicking Donald Duck, but it is held together in one area only by a seafood shack. Plaintiffs also uses the "efficiency gap" to make their case.

READ MORE: Coalition Sues Pennsylvania over Partisan Gerrymandering

For the first time federal courts are taking on and ruling against state electoral maps, not on the basis of race or other types of socioeconomic discrimination, but on the political motives of the party in power, and it is in large part because of the "efficiency gap."

Photo Credit: Christos Georghiou /

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