The reason it was called "Clubhouse POWWWW" is because Barney, in between cartoon segments, would phone lucky kids who had registered at the local McDonald's and have them play the very advanced voice-activated video game, much like Space Invaders (which of course looks hysterically primitive now). Every time you said, "POW!", the game would shoot and the object was to hit as many targets as possible. And wouldn't you know it, I was actually chosen as a contestant! I had NO proclivity for video games, and I did horribly. But I did get a "Scoop" hat for my troubles - it was a blaze-orange knitted ski hat with a HUGE pom-pon, with the words, "Scoop 11" around the hat. I stopped wearing it because I got teased at school, but oh, how I wish I still had it. I can't even find an image online to show you!
If you were a kid in Chicago anytime between 1951 and 1976, I'm sure you remember Garfield Goose, the self-proclaimed "King of the United States". A guy named Frazier Thomas created the character and was his voice (all of his friends: Romberg Rabbit, McIntosh Mouse, Chris Goose (Garfield's cousin, who was born on Christmas day, natch), and bloodhound Beauregard Burnside III were created later by Roy Brown). The show began in Cincinnati in the late '40s/early '50s but moved to Chicago in 1951. In 1955, the show settled in to its position at WGN Channel 9, where it remained until Mr. Thomas became "ringmaster" on the Bozo show, which also aired on WGN (and I remember watching at my great-grandparents' home in 1977). The puppet characters enjoyed 5 more years of celebrity on that show, where Frazier Thomas stayed until his death in 1985.
I got the card in a huge ephemera pack from Manto Fev - I just "re-found" it in one of my drawers. I'm sure this was sent in the mail for some lucky kid's birthday, maybe as a perk of being part of the fan club, if they had one. Judging by the font used for the "WGN Televison 9 Chicago", I'm going to say that this was pretty near the end of their run - maybe mid-Seventies?
While it would be totally easy to use it in artwork (replacing the "sign" with some other collaged bit), I'm going to keep this intact. It's a fun reminder of how local TV used to reign, before cable and the Internet.