The nationwide study categorized the outcomes of all 435 U.S. House races and about 4,700 state House and Assembly seats, including Indiana's 100 House seats and nine congressional races up for election past year.
The AP analysis excluded state senates because results would span multiple elections.
Republicans won an average of 67 percent of the vote in Utah's House districts previous year but won all four of Utah's U.S. House seats, giving the GOP almost one seat beyond what would be projected in a votes-to-seats ratio. It's created to detect cases in which one party may have won, widened or retained its grip on power through political gerrymandering.
Indiana House Republicans unfairly benefited from political gerrymandering in the 2016 election, according to an analysis of voting data released by the Associated Press.
Nationally, the analysis found that Republicans may have won as many as 22 additional congressional seats over what would have been expected based on the average vote share in congressional districts across the country. Some of the proposed shifts sought to move heavily black precincts - where voters overwhelmingly support Democrats - from Republican-held districts into ones occupied by Democrats.
The chief architect of a Republican legislative redistricting plan has previously said politics played a key role in drawing lines, but in ways that helped incumbents in both parties. Del.
Ultimately, Republicans picked up a 13th district in a state where registered Democratic voters outnumber Republicans by a margin of 4 to 3.More news: 6 hurt as car strikes people at Muslim celebration in Newcastle
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About 4,700 state House and Assembly seats were up for election previous year; Louisiana did not hold legislative elections in 2016.
Last fall, voters statewide split their ballots essentially 50-50 between Republican and Democratic state House candidates.
Rep. Debbie Dingell (D-Mich.) on Sunday said she wasn't predicting that Democrats would win any of the contested congressional special elections held this year.
The investigation used a new statistical method of calculating partisan advantage, developed by University of Chicago law professor Nick Stephanopoulos and Eric McGhee, a researcher at the nonpartisan Public Policy Institute of California, called the "efficiency gap".
About 75 percent of the state House races in Arkansas and SC lacked either a Democratic or Republican candidate.
"Partisan bias is distorting the composition of the U.S. House, and a handful of states are principally responsible for driving it", the Brennan Center found. Republicans may have won an extra congressional seat over what would have been expected based on the average vote share around the state that shows a large so-called "efficiency gap". In the first decade of the 2000s, about 40 percent of Missouri House races lacked major-party opponents.
Court precedent says gerrymandering can be unconstitutional, although there is no definitive answer to the question of how large an efficiency gap must be to indicate an unconstitutional gerrymander.