An unsupported claim in Rucho v. Common Cause

Maps of a Republican gerrymander of North Carolina and a Democratic gerrymander of Maryland. The North Carolina map was ruled a racial gerrymander, redrawn, and the redrawn map was immediately challenged. (From public domain images.)

On June 29th, 2019, the Supreme Court issued a ruling in the case of Rucho v. Common Cause. A 5–4 majority held that partisan gerrymandering is something that federal courts are constitutionally unable to address (link). Section II part B begins with the following inadequately-supported claim:

Partisan gerrymandering is nothing new. Nor is frustration with it. The practice was known in…