INSTITUTE INDEX: 2018 elections will test gerrymandering's grip

Brennan map of partisan bias in Congress

This map from the Brennan Center for Justice shows the states with congressional districts that are the most gerrymandered in favor of Republicans. Since this map was released, Pennsylvania redrew its districts after the state Supreme Court ruled the legislature's 2011 map unconstitutional. 

In the 2016 election for the U.S. House of Representatives, percent of votes that Republican candidates received nationally: 49

Percent of seats that Republicans now hold in the U.S. House: 55

According to Dave Wasserman of the Cook Political Report, percentage-point margin of victory that Democrats would need this year to gain a majority in the U.S. House: 7

According to the Brennan Center for Justice: 11

Last year that either party had an 11-point margin of victory in U.S. House races: 1982

Percentage-point margin by which respondents in a recent Reuters survey preferred a Democratic congressional candidate over a Republican: 9

Number of Southern states included in the Brennan Center's list of seven states where congressional maps show "consistent and high partisan bias" in favor of Republicans: 4

In the current Congress, estimated net number of seats gained by Republicans through gerrymandering: 16 to 17

Under congressional maps that were redrawn due to a racial gerrymandering lawsuit, number of Virginia's 12 seats that Democrats are expected to win if they receive half of all votes: 5

After a court ordered North Carolina legislators to fix its racially gerrymandered congressional map, number of the state's 13 districts that the Elections Committee co-chair admitted were drawn to elect Republicans: 10

Percent of the overall vote that Democrats are estimated to need to overcome North Carolina Republicans' advantage and take a fourth congressional seat: 53

In the 2016 election for the North Carolina state House, percent of votes that Republican candidates received: 53

Under legislative maps that were redrawn as part of a different racial gerrymandering lawsuit, percent of N.C. House seats Republicans won that year: 77

In the 2017 state House election in Virginia, percentage points by which Democrats beat Republicans overall: 9

Percent of seats Democrats now control there: 49

Number of lawsuits over partisan and racial gerrymandering currently pending at the U.S. Supreme Court: 4

(Click on figure to go to source.)