The Transportation Security Administration is expanding its screening of passengers before they arrive at the airport by searching a wide array of government and private databases that can include records like car registrations and employment information.

While the agency says that the goal is to streamline the security procedures for millions of passengers who pose no risk, the new measures give the government greater authority to use travelers’ data for domestic airport screenings. Previously that level of scrutiny applied only to individuals entering the United States.

The prescreening, some of which is already taking place, is described in documents the T.S.A. released to comply with government regulations about the collection and use of individuals’ data, but the details of the program have not been publicly announced...

The official added that these rules consider things like an individual’s travel itinerary, length of stay abroad and type of travel document, like a passport. If an airline has a traveler’s passport number on file, it is required to share that information with the T.S.A., even for a domestic flight.

The agency also receives a code indicating a passenger is a member of the airline’s frequent-flier program and has access to details about past travel reservations, known as passenger name records. This official could not confirm if that information was being used to assess a passenger’s risk...

Data in the Automated Targeting System is used to decide who is placed on the no-fly list — thousands of people the United States government has banned from flying — and the selectee list, an unknown number of travelers who are required to undergo more in-depth screening, like Mr. Darrat. The T.S.A. also maintains a PreCheck disqualification list, tracking people accused of violating security regulations, including disputes with checkpoint or airline staff members.

That has happened to Abdulla Darrat, an urban planner from Queens who said he was flagged for extra scrutiny all eight times he flew since June. When he tries to check in online, a message tells him to check in at the airport, where he receives a boarding pass marked with “SSSS” indicating that he must undergo enhanced screening. His name has been handwritten on a card at the podium where an agent checks passengers’ identification, he said.

“They pat me down,” Mr. Darrat, 31, said. “Then they pull out every single article of clothing in my bag. They take out every shirt and every pair of pants.”

After the checkpoint search, which includes swabbing his luggage to check for explosive residue, he said he was often stopped at the gate before being allowed to fly. He said he assumed that the extra scrutiny was because he had flown to Libya to visit relatives. He also expressed support for protests against Muammar el-Qaddafi in 2011, but the extra scrutiny did not happen until this summer.

“It adds this whole air of suspicion about me to everybody on the plane,” he said.

Anyone who has never traveled outside the United States would not have a passport number on file and would therefore not be subject to the rules that the agency uses to determine risk

Prescreening of passengers is nothing new, and we are not using any new data to determine low risk passengers. Unfortunately some have confused these programs, so we wanted to take this opportunity to make clear what we are not doing:

We are not expanding the type of information we use – again we rely on the same security information passengers have been required to submit at time of booking for many years.
We are not using car registrations or employment information.
We are not using “private databases” – the info we rely on is the same info that passengers have provided for years when they book their flight.
TSA does not monitor a passenger’s length of stay in any location.
Let’s also remember that when it comes to TSA Pre✓™, passengers are choosing to apply for this program – having determined a small fee and a background check is worth expedited screening when they travel.

TSA has a very high bar when it comes to protecting the civil liberties of the traveling public. Our job is to make sure that passengers are able to travel safely, and the programs we have undertaken are designed to meet this goal while at the same time making your traveling experience a more positive one – moving from a one size fits all approach of security to one that provides a much larger part of the traveling population the opportunity to move through security faster and with less hassle.

...At the heart of the expanded effort is a database called the Automated Targeting System, which is maintained by the Department of Homeland Security and screens travelers entering the United States...

...For instance, an update about the T.S.A.’s Transportation Security Enforcement Record System, which contains information about travelers accused of “violations or potential violations” of security regulations, warns that the records may be shared with “a debt collection agency for the purpose of debt collection.”...

...A recent privacy notice about PreCheck notes that fingerprints submitted by people who apply for the program will be used by the F.B.I. to check its unsolved crimes database...