Actually, I believe it was 1976 when the US joined the Berne Convention. There was a big noise made about Lord of the Rings being pirated by ---- company due to the lack of a US copyright filing. (Name deliberately left off.)
There was a number of (Very rare!) mimeograph books issued in the US by British authors to enforce their copyrights....
Another proud Tarnover graduate!
Remember, no matter what they say, people don't want the truth, just their prejudices reinforced. -RSE