Let's take a look at some other Mid-Continent signs...

Here are a couple of curb signs. I've seen one other style, but can't find a picture. (It's "home plate" shaped.)

This Diamond Motor Oil curb sign dates to the mid 30s.

Here's a Diamond 760 curb sign from the late 30s.

photo: Scott Shipers

Does anyone have a picture to share of the 30" NevrNox Ethyl curb sign from the 1933-36 period?