Anonymous

If you Google it, you will find arguments for both styles. It's not possessive. You would write "The nineteen twenties" and not "The nineteen twenty's" Therefore, I write 1920s. However, 1920's is commonly used and acceptable too.

Anonymous

1920s. I knew there would be people on here answering when they don't know what they're talking about! Here's a pretty authoritative source- https://www.history.com/topics/roaring-t...

Anonymous

1920's

Anonymous

1920's