Thanks everyone, this is very helpful. I am new to this forum and am still trying to figure it out. I'm based out of Phoenix Arizona, Glendale is a smaller part of town nearby. I have been into metal detecting for about a year and a half. Its difficult to find areas to hunt that date back to the early 1900's, and Ive found a few rabies vaccine dog tags but nothing that dates this old. I'm still eager to find out what significance the number plays on the tag. AZ became a state in 1912, so I was wondering if that plays into when they may have started to issue dog tax tag locally in this state. Thanks again for any and all help!