Nothing new here, but always worth remembering.
Top 10 Most Gerrymandered States
1. Michigan
Gerrymandered by: Republicans against the Democrats.
Quick Summary: This one is personal!
Notable Examples:
14th District: Jams together the African-American-dominated cities of Pontiac and Detroit, 31 miles apart. Its convoluted shape has packed in as many Democratic voters as possible...Email correspondence among GOP operatives summarized the party's control over the House mapmaking as “a glorious way that makes it easier to cram ALL of the Dem garbage in Wayne, Washtenaw, Oakland and Macomb counties into only four districts.”
3rd district: Republicans were in danger of losing as the main urban center of the district, Grand Rapids, was becoming increasingly left leaning. So they decided to add Calhoun County to the district, and jettison the rapidly diversifying southern suburbs of metro Grand Rapids. Those voters were then tossed into ultra-conservative 2nd district. The decision to split one of the main cities in Western Michigan into 2 districts was fairly clear abuse of Michigan guidelines which state districts should break as few county lines as "reasonably possible."
Michigan should drop down the list when in 2022 it is redistricted after a grassroot led movement to have boundaries drawn by an independent commission was overwhelmingly backed in the 2018 midterms.
2.Ohio
Gerrymandered by: Republicans against the Democrats.
Quick Summary: Unfairly distributed districts in a partisan way.
Notable Examples:
9th District: Designed by the Republican who controlled state mapmaking in 2001 to get rid of a Democratic House member, by making two incumbents living more than 100 miles apart compete for one seat. A panel of federal judges in Cincinnati described the district as "a bizarre, elongated sliver of a district that sever numerous counties."
4th District: Known as "the duck," with its bill up in the northern counties just under Lake Erie. Portions are near Cleveland, parts are close to Columbus, and another portion is near Dayton.
3. Wisconsin
Gerrymandered by: Republicans against the Democrats.
Quick Summary: Unfairly distributed districts in a partisan way.
Summary: The Wisconsin Assembly became notorious for its gerrymandered districts after the 2018 election, when 63 of 99 seats went to Republicans despite the party winning only 46% of votes. The district maps drawn by Republicans in 2011 were so unrepresentative of the majority of voters that a study last year by Harvard’s Electoral Integrity Project gave them a score of just 3, out of a possible 100 for perceived integrity—lower than any other state.
4. Maryland
Gerrymandered by: Democrats against the Republicans.
Quick Summary: Uses broken districts to give an advantage to Democrats.
Notable Examples:
3rd District: Visually, Maryland's 3rd is atrocious. And the narrow nature of most of the district — constructed to favor Democrats — makes it difficult for residents to know whether they are physically in the district or not.
6th District: Drawn by Democrats to pack as many Republican voters as possible into a single meandering district.
5. Louisiana
Gerrymandered by: Republicans against the Democrats.
Quick Summary: Combined Baton Rouge and New Orleans into one district to minimize Democratic votes.
Notable Examples:
2nd District: It selectively fractures the city of Baton Rouge into two to ensure the 6th remains red. Republicans moved a large number of African-Americans who live on the north side of Baton Rouge into the heavily Democratic 2nd.
6. Texas
Gerrymandered by: Republicans against the Democrats.
Quick Summary: Has tried to propose districts that would unfairly affect minority voters.
Notable Examples:
2nd District: The result of extreme Republican gerrymandering in Texas. If the district were less oddly shaped and contorted it would actually be quite difficult for a Republican to win in this area. Demographic and population shifts show that the Houston metropolitan area is becoming increasingly more Democratic.
35th District: If Austin was all in one congressional district, it would most certainly be a deep blue bastion. Instead the Austin area is chopped up and dispersed among six different districts. The result is a city with a big delegation, but most of the members aren't focused on the issues affecting Austin's inhabitants. And five of the six districts are now represented by Republicans.
7. Alabama
Gerrymandered by: Republicans against the Democrats.
Quick Summary: Has drawn district boundaries to balance out city voters with rural voters.
Notable Examples:
7th District: Proof that racial gerrymandering is partisan gerrymandering, and vice versa. It is heavily Democratic and gives off several narrow tendrils that encompass major black population centers, including far-off Birmingham.
<Edited 8-10 & dishonorable mentions following criticism from Drakle>
8. Utah
Gerrymandered by: Republicans against the Democrats.
Quick Summary: Divides Salt Lake City into surrounding rural districts.
Notable Examples:
2nd District: After the Democrat Jim Matheson was elected in 2000, the Utah legislature redrew the 2nd congressional district to favor future Republican majorities. The predominantly Democratic city of Salt Lake City was connected to predominantly Republican eastern and southern Utah through a thin sliver of land running through Utah County. Nevertheless, Matheson continued to be re-elected. In 2011, the legislature created new congressional districts that combined conservative rural areas with more urban areas to further dilute Democratic votes.
9. Kentucky
Gerrymandered by: Republicans against the Democrats.
Quick Summary: Places urban populations in rural districts.
10. Pennsylvania:
Gerrymandered by: Republicans against the Democrats.
Quick Summary: Divides its major urban areas among other districts.
Dishonorable mentions
Arkansas
Gerrymandered by: Democrats against the Democrats (Best not to ask), redistricting then blocked by the Republicans.
Quick Summary: Has drawn district boundaries to balance out city voters with rural voters.
Georgia
Gerrymandered by: Republicans against the Democrats.
Summary: From a visual perspective, Georgia's map is among the stronger ones you will currently see. That said, there's an issue with the three counties that are the most populous in the state and form the core of Atlanta's metropolitan area. They are subdivided to a troubling extent. Having a county split three or more ways is less than ideal for its residents.
North Carolina
Gerrymandered by: Republicans against the Democrats.
Summary: North Carolina would have topped the list in the past. However in 2016, the court ruled that the maps were racial gerrymander and ordered the drawing of new maps. The end result is North Carolina is highly likely to elect five Democrats to Congress in 2020, two more than in most of this decade. Aggressive mapmaking by the Republicans who dominate the General Assembly had resulted in just three of 13 House seats going to Democrats even though their slate of candidates was securing about half the statewide congressional vote — and a slim but clear majority in 2018. The new map still favors Republicans, but at least much less blatantly.
https://thefulcrum.us/worst.../1-beside-lake-erie
https://worldpopulationreview.com/.../most-gerrymandered...
https://en.wikipedia.org/.../Gerrymandering_in_the_United...
https://psmag.com/magazine/among-the-gerrymandered
https://readsludge.com/.../in-heavily-gerrymandered.../