[Publius]

And Reynolds v. Sims, aka "One Man/One Vote", eliminated rural representation in state legislatures.

[Jacquerie]

Beat me to it.

If Your State is a Mess . . .

[The_Reader_David]

Reynolds v. Sims is generally ignored in the list of harms leftist majorities on SCOTUS have inflicted on the Republic. Admittedly Roe v. Wade was worse, but in terms of harm done, it’s a near run thing between Reynolds v. Sims and Wickard v. Filburn for second place.