Red Crown Gasoline 42" vintage sign

A 42" one sided porcelain Red Crown Gasoline vintage sign.
The 2 circles are not blue but appear to be the metal of the sign covered
with porcelain. Below the O & L in gasoline in very small letters
it says Alliance Advertising Co. Below that it says ADV - 285-3. Those
numbers are so small that they may not be accurate. There is about
a quarter size chip out of the "S" but didn't perforate the sign.
Also a small, perfectly round chip out of the "N" the size of a BB.
The red letters appear to be handpainted then porcelain was applied. The sign is a perfect circle. The discoloration on the left is where some porcelain is missing but does not affect the edge.

Can someone give me some history on Alliance Advertising? A date
range and possible value for the sign? Have purchased some small vintage porcelain gas signs but nothing this size.

I purchased it from an estate sale. Because of other items in the home, I believe the owner may have worked for Amoco/BP in the Chicago area.
Thanks