While working to compile photographic images for my DFW in vintage photos post a few months ago, I managed to get my hands on an old postcard for the city of Plano. If you didn't know, finding and acquiring historic images of the city of Dallas proper is not especially difficult; all you really need is a bit of vigilance and a healthy dose of patience while keeping an eye out at antique stores, estate sales, and online auctions. Just give it some time, and the photos will turn up. Finding interesting period photos of the suburban areas, though, can be considerably more difficult. So it was with some delight that I acquired this particular real photo postcard. And, unlike other similarly aged RPPCs that I've found, this one came with a mystery attached: where was the Plano Dam?