That definitely was not an East Coast thing. I remember seeing one for the first time about 10 years ago and saying, "WTF?!?"
You're probably too young, Ben. These things were around in '77 or so...I was 12...you were probably in diapers or just a twinkle in your daddy's eye...
Maybe it was just an Oregon thing...it looks like the guy who invented the things was from Oregon (
http://www.geocities.com/Heartland/Plains/9338/swing.html).
Anyway, I had a couple of buddies that had them. They were certainly a trick to ride...especially being used to the mean a$$ machine I rode at the time: A silver Schwinn Varsity 10-speed:getsome:
The fun thing was watching my buddies when they tried jumping 'em of the ramps we built in the yard; always a lot of thuds