Brennan Center for Justice
To gauge where this type of gerrymandering is taking place and its magnitude, this report used election results [from 2012, 2014, and 2016] in states with six or more congressional districts to assess the extent and the durability of “partisan bias” — the degree of systematic advantage one party receives over another in turning votes into seats . . . It also looked at the relationship between the body that drew the maps and the degree of bias observed.