STOP CARRYING YOUR SOCIAL SECURITY CARDS AROUND!!!
I have heard the argument a dozen times that people (Dr. offices, etc) always ask for it so you feel that it's necessary to carry it.
I haven't carried around any Social Security Cards in well over 10 years. I keep them locked up in a fireproof box and only take it out if I have been specifically required to bring it somewhere. The only times that this has been required is applying for a passport, starting a job, or enrolling a child in school. I have been told in other instances that it might be necessary for me to provide it, but if it is, they will have me bring it in later. I don't know my children's number and when the doctor office asks for it, I tell them I don't know it or carry it. They have always told me that it helps process insurance faster but isn't required. If they run into any trouble, they will call back to get it. I have never had a problem or even had them call me for it. When I supply my own number, I watch the employee to see how they handle that paperwork and have once asked a receptionist at a doctor's office to please take my paperwork off the counter since all my information was exposed to patients coming and going.
That number equals your identity, your credit and potentially money. Identity theft is a hard crime to stop and pays highly for the criminals . Worst of all, it often has less risk of being caught than many other crimes. Stealing, using, and even selling Social Security Cards is a big "business". Children are often targeted too because they haven't ruined their credit yet and nobody else is going to use it for many years so no one will catch if credit cards are being opened in their name. If you lose it or it get's stolen, it is a nightmare to change to a new number and repair damage done.
This is an excellent related article on the subject I found and thought I would share.