Unusual Porcelain Sign - Maiden Lane

Bought this 24" diameter porcelain sign by United about 40 years ago in Maryland. At that time, I was told the sign was used at Service Stations during WWII to show which gas lane the gas was being pumped by women. Have never been able to confirm this, as I've never found anyone who has any knowledge of this sign. It's one sided with one color (brown on a white background) with four equally spaced small hole around the edge, and one in the middle. It's a great story and one of my favorite "things" I've picked up over the years. Sure would like to know the truth about it.