World wide. Slowly going out of fashion now.
I guess I missed the memo.
It's been around for a long time, but isn't often obviously labeled (except during events like Steampunk World Fair, Maker Faire, etc.). Did you ever watch the TV series, "Wild Wild West"? It's probably one of the earliest forms of steampunk in mainstream media.
Hacking old gear to make it do new things (or hybridizing it with new tech) could be considered a form of steampunk (though, probably more correctly retrofuturism or futuristic retro).
I still like it. Some of it is weird, but some is wonderfully creative.
I grew up on it... Artemis Gordon was one of my childhood "media father figures". Of course, as I grew up and became more cynical, Dr Miguelito Loveless not only became a more understandable, but even somewhat sympathetic character to me.
If you hated his testosterone-hosing depiction of Pappy Boyington, you should check out Conrad's "James West"; he is much more prone to self-deprecating humor and while still a raging bundle of machismo as was the fashion, he's at least somewhat endearing in his boy-scout facade.
If you can handle the "emo" romance novel overtones and serial soap opera format,
Girl Genius is one of the internet's oldest running webcomics, and it is pretty much 100% SteamPunk. If you're not that artsy-fartsy, the "Hellboy" movies have good examples as well.
mnem
'Punk from way back.