White Stop Sign with Red Lettering

HI, I found this Stop sign on an abandoned warehouse wall. I thought it was interesting because of the white background with red letters. I cannot find and markings. It is 24in x 24in. Looks to be hand painted? These are the original colors however, it definitely has not been painted over. Can anyone give me even an inkling of what this might be. I have scoured the internet to no avail! Thank you very much!!