Here's an article I wrote on this #history (mostly focuses on the labor side of things, but gives an overview of the earlier efforts to criminalize birth control). In the late-19th and early-20th century, some key methods the federal government used to policed morals, sexuality, and labor radicalism included mail surveillance, restriction, and criminalization. During and after WW1, this grew to a nationwide system of restricting the mail of any speech deemed un-American: https://acrobat.adobe.com/link/track?uri=urn:aaid:scds:US:709dda7a-c2b3-46a0-962b-03220d30f5b4