Millions of international travelers from a few select countries won't have their bags X-rayed a second time when making connecting flights in the United States, under a law President Obama signed Thursday.

The so-called "No-Hassle Flying Act" gives the Transportation Security Administration the authority to waive domestic screening for luggage from foreign airports that already passed through preclearance security overseas. The Senate and House each approved the legislation with voice votes.

"Requiring luggage to undergo the exact same screening process twice in one flight puts a burden on our international aviation security system and creates an unnecessary hassle for travelers," says one of the sponsors, Sen. Amy Klobuchar, D-Minn.

U.S. Customs and Border Protection has 15 facilities at foreign airports enabling travelers to have their luggage precleared, to shorten lines when arriving in the United States.

The airports comprise nine in Canada, two in Ireland in Dublin and Shannon, and four in the Caribbean, in the Bahamas, Bermuda and Aruba. The checkpoints screened 15.2 million travelers last year.

Despite the overseas screening, TSA has been rechecking the bags before placing them on connecting flights in the United States. That hitch can make domestic connections trickier.

TSA had earlier proposed similar legislation, in an effort to streamline cross-border traffic.

Airlines welcomed the legislation as a step toward making travel more convenient while keeping luggage secure.

"This is a smart, efficient way to streamline travel, boost tourism and lower costs while maintaining the highest security standards," says Nicholas Calio, president of the industry group Airlines for America.