I don't understand why there's a want or a need for a national ID system. If you're a citizen, you already have Social Security documentation, and probably a passport/driver's license.
A national ID is a Single Point of Failure. I have had several cops / security folks tell me that a collection of documentation greatly increases the difficulty of forgery, because they have to be mutually consistent over space and time. A variety of documents provides a multitude of entry points and traversals for even a cursory on the spot casual interrogation. For example, some of the digits of the SSN associate with certain states at certain times, so even if the SSN Card isn't produced as ID, a question to tell the SSN orally, Followed by a remark like "Do you parents still live in State X" can trip someone up. Also, some states have had difficulties with corruption and counterfeiting in DL bureaus, but perhaps not all states at all times. Relative wear, like marks and de-lamination, also are giveaways, along with other seemingly innocuous contents of a wallet. Collections of anything will exhibit patterns of differences and similarities from individual to individual, and will be characteristic of a given 'locale', and these will alert an experienced observer. A national ID would tend to be adopted by any and all agencies as proof o person, if just as a cost and complexity saving measure. But it's that same complexity which trips the impostors.