Help with unusual Mexican Border / WWI dog tag

[Chris]

I have seen a lot of WWI tags, but the format on this one is odd to me. It has "3rd Co." and "SanFransisco". No regiment or unit mentioned. I was wondering if anyone might know e actly what period it is from and,/or who used this sort of format on dog tags? Thanks for any help.

[pwcosol]

Think what you may have is a C.H.G. (California Home Guard) tag. The "dogtags" were first introduced in 1906. From what I read, U.S. Army divisions were divided into Companies with a letter prefix (i.e. Company C). It appears the Guard units were designated by a equivalent number (i.e. 3rd Company). I found this link and I think you might find it helpful, detailing the history of the C.H.G. and California Militia (the 3rd Company is mentioned in the text):

 

https://www.militarymuseum.org/SanFranciscoHG.html

[jprostak]

Ernest A Whitney was in the 2nd Company of Coast Artillery, Harbor Defenses of San Francisco.