Oh, my. My mind is blown. I highly, highly recommend this article about a slice of history of which I knew nothing, most especially to my white readers in the USA:
The Rise and Fall of an All-American Catchphrase: 'Free, White, and 21'.
Note that it has quite a bit of A/V content; there's a YouTube video at the start that you should really watch at least the first third of before trying to read the article, and then there's stills from it and other illustrative images (shots of job ads, etc) throughout.
Maybe more commentary later.