Evan Hendricks, editor of the "Privacy Times" newsletter, says the evolution of Social Security number is a symbol of what happens to personal data in the modern world.

Hendricks: They said it was only going to be for the purpose of tracking your Social Security account, and then slowly and quietly it was used for driver's license records, now you have to give it to your bank, all government agencies use it as the identification number, so the original promise that it was only going to be used for one purpose was one of the great lies to the American people.

And some Americans are rebelling against the Social Security number. In the last few years, groups opposed to the number have proliferated on the Internet, with Web sites and mailing lists. Many groups are motivated by religious beliefs. Scott McDonald, a construction worker in Alabama, runs a Web site known as "Fight the Fingerprint."

McDonald: In the book of Revelation it talks about this numbering system that a kind of worldwide government will require people to have to buy or sell. And I see that happening with the Social Security number. Whether it is the mark of the Beast or not, it conforms to all the criteria.

		"And he causeth all, both small and great, rich and poor, free and bond, to receive a mark in their right hand, or in their foreheads: And that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name." - Revelations 13:16

McDonald: That a single identifier can bring all that information together in one location, which makes it, in essence, one huge, large database. Everything about you can be collected through the Internet right now using that number.

Hostility to universal identification systems runs deep in American culture, something that may explain why it took decades of incremental change for the Social Security number to become the national identifier. Representative Ron Paul of Texas, one of the most outspoken privacy hawks in Congress, says his constituents are very suspicious of the number.

Paul: We've done some polling, and 80 percent of the people in my district and across Texas are very concerned and upset about the trends of the federal government toward using the Social Security number the way they do.

The most recent flashpoint in the battle over the number has been the 1996 Illegal Immigration and Reform Responsibility Act, which directed states to require Social Security numbers from all driver's license applicants. Congressman Paul interpreted the law as an effort to use the Social Security number to create a de facto national ID card by yoking all the state driver's license databases together with the Social Security number as the common denominator. The system would have taken effect in October 2000. But this fall, Congressman Paul and other conservative Republicans got the House and Senate to repeal it.

Congress has put some other limits on the government's use of the number. Most government agencies can ask for the number, but usually only on a voluntary basis, and they're supposed to tell you when it's voluntary. Only a few agencies can demand the number outright, most notably the Internal Revenue Service.

The private sector, on the other hand, is free to demand the Social Security number, whenever it wants do; a situation that sometimes leads to a test of wills with customers. Privacy advocate Twila Brase describes her experience with a nurse's aide at her doctor's office.

Brase: ... and so she said "Oh, I see you didn't fill in your Social Security number, and could I have it?" And I said, "Well, I don't give it out." And she said, "We have to have it." And I said, "No you don't, you can just find another number," at which point she tried to leaf through my entire medical record to find the Social Security number, which I'd never given. And then she was frustrated, and she said, "Fine. I guess we will."

		Links: Fight the Fingerprint A site opposing biometrics and the use of the SSN as an identifier Grassroots Granny An activist site opposing the implementation of a national ID number. The National Organization for Non-Enumeration Educates Americans about their rights and responsibilities under the Federal Social Security Act

Brase, who runs a lobbying group known as Citizens for Choice in Health Care, says although she makes it a point to withhold her number, she understands why most Americans give in.

Brase: If you're not a nurse, not part of the medical profession, you think that possibly not giving out your Social Security number will be detrimental to your health. And so, the pressure is on to just comply.

So is it worth all the time and effort to be stubborn about your Social Security number? Robert Gellman is a consultant who has worked on privacy issues in and out of government since the 1970s. He says people should protect the number, but they shouldn't think that's enough to protect their privacy.

Gellman: People react emotionally to the disclosure of the Social Security number, but they may pay less attention to other substantive bit of information about themselves, where they work, how much they make, and that sort of thing.

Gellman says in some ways, the six-decade-old controversy over the dangers of a national identity number has been overtaken by technology.

Gellman: Linking records is not that difficult anymore, even if you don't have a common number. You can do fuzzy searching to match names, even if the names are in different forms, and addresses, and it's actually not that difficult.