Do the 20's, 30's, 40's etc always reference the previous century or have they been specially used for the 20th century.

by deepinabox

I'm wondering what we refer to the 20's in the 22nd century.

Thanks.

zubatman4

I heard somewhere that it began in the 1890's. Let me see if I can find a source on that one.

JiveJoseph

I bought a song recently from an album released in 1939 called "The Gay '90s", obviously refering to the 1890s. I also semi-remember seeing this abbreviated notation a few times in the Sherlock Holmes series, but I can't remember or quote a specific example.