But as the busy summer travel season kicked off, the federal Transportation Security Administration tried to offer travelers some relief after weeks of slow-moving lines blamed on an increase in the number of air travelers and a shortage of TSA security officers.
A TSA spokesman said the extra dogs would remain well beyond the holiday.
At Hartsfield-Jackson Airport in Atlanta, known as the world's busiest, all 16 security lanes at the main checkpoint were open Friday morning as a bomb-sniffing dog and its handler walked among waiting passengers. Wait times were slashed to less than 15 minutes, compared with backups of nearly an hour in recent weeks.
"All the natives were telling me, 'Brace yourself,'" said Carl Pluim, who arrived in Atlanta to fly home to Denver. "I left myself two hours before my flight, so I think I'll be OK."
When she flew barely two weeks ago, LaGretta Watkin recalled security lines that were "so chaotic" that travelers "could barely move."
"But today it's smooth sailing and refreshing," Watkin said as she started a trip from Atlanta to Jacksonville, Florida. "And I'm loving it."
The TSA began deploying extra canine teams to the busiest airports months ago. While the goal was to shorten waits at larger airports, the reshuffling could also result in longer lines at airports that lost dog teams.
The dogs "have the ability to screen large groups of passengers for explosives, making the removal of shoes and laptops and such unnecessary," TSA spokesman Mike England said.
The agency has 900 dog teams nationwide, England said. He declined to say which airports they were sent to for the holiday weekend or how long they might stay.
"This is not just for Memorial Day weekend," England said. "I wouldn't expect that it would go away any time soon."
At O'Hare Airport in Chicago, which had some of the worst screening meltdowns in recent weeks, lines moved briskly Friday, though still swelled at times. Typical security procedures appeared to be in place, with passengers removing belts and shoes and taking computers from bags and items out of pockets. Bomb-sniffing dogs were making rounds in pre-security areas.
Terri Hale, arriving in Chicago from Cleveland, said security there seemed, if anything, tighter than usual. Passing through the millimeter-wave scanner, she was stopped and asked to empty her pocket for what turned out to be a tiny piece of foil from a gum wrapper.
"When she found that I was like, OK,'" Hale recalled with a laugh, as a security dog sniffed around her in the O'Hare baggage claim area.