CA birth certificates have never displayed a SSN. As a matter of convenience a mother is offered an option while hospitalized of having the Dept of Health pass on the identifying information (displayed on a BC) to the Soc. Sec. Adm., which in turns issues a card to the mother on behalf of the newly born child. This option was offered beginning about 10 years ago when IRS required each dependent's SSN appear on the 1040 [FYI 8 million dependents disappeared after this requirement.] Banks require a person's SSN for all interest bearing accts to ensure that interest is correctly attached to the SSN of an account holder (otherwise 1099 information would be easily subverted). Non-interest bearing acct such as checking do not need a SSN. Those who fail to give a SSN (an incorrect or a SSN mismatching the surname contained within IRS data systems (updated periodically by SSA) are subject to a mandatory withholding of tax. Banks or any institution requiring (for other than income tax purposes) a SSN do it exclusively for their private internal purposes. Those who do not qualify for a SSN (somewhat ironically including terrorists on a tourist visa) can prove their disqualifiication and sign IRS form W-8 form when opening an interest bearing bank account to avoid tax withholding. There is absolutely no reason non-governmental entities cannot establish unique PIN type identifiers. Even SSA no longer issues centrally issued correspondence with more than the last 4 digits (to my knowledge this includes at least the every 3 year benefit estimates and annual COLA letters). Contact with any SSA office may find this policy includes other correspondence as well. Some states (thankfully not California) actually use a person's SSN as the driver's license number. I could rattle on more about this... but I won't.