Similar sign from Sinclair Collectors guide and text showing dates when Sinclair used the Mobiline name. So it looks like your sign dates from 1928-1931.
The book this picture is from is from 1997, so don't listen to that $350-$500 valuation. I would think it's about 3 times that.
Again, very cool sign!
Last edited by Steven C.; Wed Dec 20 2017 02:09 AM.