nice postcard, Leon. And great find. I agree with some of the others that it makes sense to promote the town you find the most famous person to come from the town and put him on a postcard. Then you sell that postcard with the Weiser Wonder on it.
I can tell you that there was a high school that was a rival to Grant Hill (of NBA Basketball fame) right near where I grew up. Everyone would talk about the school that Grant Hill was from. But that was after he made good in the NBA, not before.
Same thing with Jim Thorpe, PA being founded after he made it big.
http://en.wikipedia.org/wiki/Jim_Thorpe,_Pennsylvania
Happens a lot in sports when the player makes it big and the home town then claims them.
I'm sure many postcards are written well after the date that they were written but in my (limited) experience, I've seen the majority of postcards written around the date they were issued (within the year?) Very unscientific, I know, but that has been my experience.