Gerrymandering, example of

Texas’ 35th district from assholedesign

ghalta
Austin is the largest city in the country that doesn’t have a congressional district centered in/on it, but is instead split into five congressional districts – 21 that stretches out into the hill country, 25 that reaches up into the DFW suburbs, 17 that includes Waco, 10 that stretches to the Houston suburbs, and 35 shown above. The goal of the Republican-dominated legislature that created these districts was openly and intentionally to dilute the influence of Austin’s liberal voters in electing the Texas congressional delegation. In 2018, for example, Democrats won about 47% of the overall state’s congressional vote, but only won 13 of the state’s 36 districts thanks to gerrymandering such as above.

Bounty1Berry
I could see odd shapes if the goals were to try to have approximate equality of population, to follow landmarks like rivers and highways, and to minimize splitting of other government entities (cities/counties) across districts.