Where is gerrymandering most notable now?

Currently, rigged maps tend to be most prevalent, and most tilted, in states under Republican control. That is in part because Republicans did exceptionally well in the 2010 elections, giving the party far wider control of state legislatures, which oversaw redistricting after the 2010 census. The national Republican Party had poured money and expertise into state legislative races with the specific aim of gaining control over redistricting; the Democratic Party had not.

Many political scientists consider the House maps in Republican-controlled states like North Carolina, Michigan, Ohio and Texas to have the most pronounced partisan slants. (Pennsylvania was also on the list until its map was redrawn last year.) Among Democratic-held states, Maryland, Illinois and — to some observers — California are regarded as the most tilted. Illinois is especially notable for its “pizza slice” division of metropolitan Chicago, using generous helpings of urban Democrats to offset the heavily Republican suburbs in district after district.

Perhaps the most notable recent example is the Wisconsin State Assembly, whose members are all elected every two years. Wisconsin is a battleground state that swings from Republican to Democratic and back again in statewide elections for governor, United States senator and other offices.

After the Republican majority redrew the Assembly district map in Wisconsin in 2011, the party won a supermajority in the chamber. Then in 2018, Republicans retained that supermajority, even as Democrats won every statewide office.