More than 1.5 million travelers have signed up for PreCheck, the pre-screening program that streamlines the security checkpoint process at airports. (George Frey/Bloomberg)

Since October 2011, more than 1.5 million travelers have signed up for PreCheck, the screening program that streamlines the security checkpoint process at airports. The Transportation Security Administration hopes to add more to the ranks.

Select processing centers across the country will expand their hours starting this week. IdentoGO centers, which provide enrollment services for the agency, will increase the hours they are open on weekdays and introduce Saturday hours.

From Oct. 3-Nov. 21, more than a dozen locations will test Saturday hours. Among the sites: the IdentoGO Center on Duke Street in Alexandria and application outposts at airports in Palm Beach, Fla.; San Francisco; Tampa; Boston; St. Louis; Los Angeles; and Dallas-Fort Worth. Multiple locations will boost their weekday hours, including centers in Chicago, Salt Lake City and Columbus. The TSA lists locations and operating times on its Web site.

In addition, H&R Block offices in 27 states are planning to provide application services during normal business hours.

In the PreCheck program, passengers do not have to remove their shoes and light outwear when passing through security checkpoints, and they can keep laptops and approved liquids in their cases and carry-on bags. Currently, 331 enrollment sites — 37 outposts at 34 airports and 294 alternate sites — enroll 4,875 people daily. With the expansion, the agency can add 2,300 more travelers per month. The program costs $85 for a five-year membership, and travelers must submit to a background check and interview.

More from Travel:

Uber and Lyft users, your ride to D.C. airports is about to get costlier

At Dulles Airport, skip the Cinnabon and shop for the runway

Don’t get stuck in the millions-strong surge of passport applications. Renew now.