if nothing else this is food for thought.when i drive our second car the only ID is the wallet in my pocket.
something the rescue crew could see to find out who i am while they are prying the car apart to get to me would be a big help for the medics.
I have to tell you, as an EMT x 8 years, I really didn't care who you were. I sure as heck didn't care what blood type you were, or who your ICE contact was.
Now at the hospital it might be useful, mainly for medication or allergy information. Or, ultimately, who to contact to pick you up.
Oh, and MOST hospitals in the US use your date of birth, not your SSN, as your second patient identifier. Might be worth tossing that dog tag and getting one that has your DOB.