If you knew this, you are either very old or spend a lot of time watching old movies from the 1920s or 1930s. "I'm free, white and 21" was a popular catchphrase nearly 100 years ago in American culture, as reflected in Hollywood films.
Jezebel magazine assembled this video montage of scenes from early talkies and silent films in which characters used the phrase -- or variations playing off of it.
What does this say about that era? Perhaps that it was commonly accepted that being black was a disadvantage?