There was a time when millions of Americans knew everyone -- or almost everyone they dealt with.
Before the giant chain stores, people went to the corner store, where the owner greeted them by name. That was a system of identification that was based on familiarity. But today, across America, things have changed.
"Because of the mobility of our society, that system of identification is broken down," said Derek Smith of ChoicePoint. "We've got to find a different way in which to be able to get that same information, to re-instill, in many ways, the best of small-town America."
ChoicePoint is one of the biggest of a growing group of companies that accumulate information about Americans' everyday lives, mining data from various sources and selling the information to others.
But in the post-9/11 era, such companies have not only attracted retailers looking to serve their customers better, but the government as well.
In a world that is more dangerous, the government has become convinced that knowing for certain who it is dealing with has become the key to security.
And that knowledge can start with something as simple as a phone call to a store.
"Think about the time you call to buy a book or a sweater," said journalist Robert O'Harrow, author of "No Place to Hide: Behind the Scenes of Our Emerging Surveillance Society."
As soon as your phone number pops up on the operator's computer screen, the networks of another data company, Acxiom, can append links to information from a wide range of databases that tell the operator not only your name, but also your estimated income and even the kind of car you drive, said O' Harrow, who collaborated with ABC News on the broadcast "Peter Jennings Reporting: No Place to Hide."
From that information, and much more, marketers -- and now, perhaps, government investigators -- can study what people are likely to do, what kind of attitudes they have, what they buy at the grocery store.
"This is what the data analysts are doing 24 hours a day," he said. "And, in many cases, they're not even doing it, it's the computer intelligence software that's deriving these conclusions."
ChoicePoint once primarily used this information to do background checks for corporations, but increasingly, it works with the nation's intelligence agencies, looking for people who might threaten the country.
"These companies are, in essence, becoming private intelligence operations. They collect information, they analyze it, they find links among people, they look for tendencies, and they do it much faster than traditional intelligence services were ever able to do," said Harrow.
There certainly is an argument to be made for the government to engage in information-sharing.
Take the example of 9/11 hijackers Nawaf Alhazmi and Khalid Almihdhar. Even before the attacks, they were already on U.S. government watch lists because of possible links to the bombing of the USS Cole in Yemen in October 2000.
But federal agencies like the CIA and FBI failed to share their information with each other. They were not technologically nor bureaucratically equipped to do so, and they failed to connect the dots that might have led to the unveiling of the plot.