The Associated Press used an “efficiency gap” analysis to examine congressional elections in 2024 and other recent presidential election years.

The test — designed by Eric McGhee, a researcher at the nonpartisan Public Policy Institute of California, and Harvard Law School professor Nick Stephanopoulos — identifies states where one party is extraordinarily efficient at translating votes into victories in legislative districts. The larger the efficiency gap, the greater the advantage that either Democrats or Republicans received from the way district boundaries were drawn.

The formula also can be used to calculate how many additional seats a party won beyond what would have been expected given their share of the vote. These are referred to as “excess seats.”

The formula focuses on the

See Full Page