Back in the '70s-'80s, Americans were recommended to engrave serial numbers on their valuables, equipment, kitchen appliances, jewelry boxes, drill bit cases/metal toolboxes (etc.) by law enforcement, insurance agents, and neighborhood watch programs... and if you didn't have a serial number, you were advised to use your SSN 😮

This idiocy was mainly because back then, SSN was not really used for much, but it was a unique way to verify your identity.