The Iron Heel (1907)

The earliest warning here, and the most openly partisan: Jack London imagines American wealth fusing into an Oligarchy that crushes organized labor and the socialist movement led by Ernest Everhard. The cleverest touch is the frame. The story is presented as Avis Everhard's manuscript, annotated by a historian writing centuries later, so the reader always knows the Oligarchy eventually falls but not how much it costs first. Start here for the left's oldest fear about concentrated money buying the state. The speeches run long, but the slow tightening of courts, press and police still reads as uncomfortably plausible.