Holiday travelers line up for one of the TSA security checkpoints at Ronald Reagan National Airport in Washington on Nov. 26. (PAUL J. RICHARDS/AFP/Getty Images)

The Transportation Security Administration merrily tweeted photos of short lines at airport security checkpoints over the heavily traveled Thanksgiving weekend, and now it plans to make a key reason for those shorter lines more readily available.

Travelers who use the TSA’s Pre-Check program get to keep their shoes, belts and sweaters on and do not have to pull their laptops from cases or display their baggy of liquids as they hustle through special airport checkpoint lines.

Their carry-on luggage still passes through X-ray machines, and they still must step through metal detectors.

The TSA says that more than 25 million fliers have used the zip-through-security program since its soft rollout in 2011.

Now it is opening a registration Web site, sign-up centers at major airports and a few downtown locations nationwide, with the first at Indianapolis International Airport this week and one set to open at Dulles International before year’s end.

Opening the enrollment centers, 300 in all, will be a step toward TSA Administrator John S. Pistole’s grander plan to reduce the security hassle for low-risk passengers so his workers can focus on those who give some reason for suspicion.

“TSA Pre-Check is enabling us to move away from a one-size-fits-all approach to transportation security,” Pistole said.

The TSA says someone who shows up at an enrollment center will spend about 10 minutes (not counting any wait time) signing up for the program. It requires a background check, fingerprints and an $85 fee for a five-year enrollment. A passport, required for some other programs, is not necessary.

Members will receive a “known traveler number” to provide to airlines when making a reservation. That makes the traveler eligible for the speedy line at 102 big airports or when flying with seven airlines, including all the major ones.

So what is new today about a program that has been around since 2011 and has been used by 25 million people? The surprising answer is that until Tuesday, there has been no way for the average passenger to directly enroll in Pre-Check.

Many of those who have used it are members of another program called Global Entry. While Pre-Check is a good fit for domestic passengers, Global Entry requires presentation of a passport to gain membership and is of particular benefit to international travelers. Among its benefits is expedited reentry into the United States after travel abroad.

Pistole opened the program to about 450,000 more randomly selected passengers per day in September. Those passengers do not know they have been selected for the faster lines until they receive their boarding pass or, in cases where the designation has been coded, when they present their boarding pass at a security checkpoint.