DENVER — Americans taking to the air and roads for Thanksgiving will battle both the crush of fellow travelers and security hassles brought on by a State Department global travel warning.

AAA, formerly known as the American Automobile Association, predicts that 46.9 million Americans will travel more than 50 miles from home this holiday, the largest number since 2007. Lower gas prices,   spokeswoman Yolanda Cade said, are an “early holiday present” for drivers.

Luke Jensen, who lives in the Des Moines area, unwrapped that holiday present early: He and his fiancée packed their four kids into their new full-size SUV on Friday and drove 16 hours to Colorado for a ski vacation. The lower gas prices left more money in the Army veteran’s pocket, and  Tuesday he took the family horseback riding with the unexpected extra cash.

“We would have come out anyway, but we wouldn’t have done as much. That’s really helping us,” Jensen said. “The kids are really excited.”

About 25 million people will fly during the Thanksgiving holiday, and most will fly domestically, Airlines For America, which represents air carriers, said in a statement.

The State Department’s worldwide travel alert cast a shadow over air travel for many Americans. The alert, in the wake of the attacks Nov. 13 in Paris, warns that terrorists may strike at sporting events, theaters and aviation services. The TSA declined to specify what additional security steps it had taken but acknowledged travelers might see longer security screening lines.

“You couldn’t get a tube of chapstick through,” said Bangor, Maine, travel agent Diane Bean, who flew through London’s Heathrow Airport on Saturday.  “The security was incredible.”

Bean, who runs Off On Vacation Travel and flies frequently, said she had never seen screeners so businesslike and focused on their work. Her checked luggage still hasn’t arrived, which she attributes to equally intense security screenings in Paris, which she also transited.

Redwood City, Calif., resident Matt Reyes said he was getting ready to fly home via London from a work trip to Italy on Monday when his mom texted him about the alert, telling him to be careful. He said security screeners at Heathrow  in London pulled aside his carry-on to remove a bottle of face wash that screeners in San Francisco hadn’t seemed concerned about. A screener explained the concerns about liquid explosives, he said,  citing the destruction of a Russian airliner with what terrorists implied was liquid explosive.

“In Heathrow, it was very clear, very straightforward,” said Reyes, who works for GoPro.

Reyes said he reassured his mom about his travel plans and said he wasn’t going to change anything. He said everything contains some element of risk or danger, and  he wasn’t going to allow unspecified fear to control him: “Terrorism is about inspiring fear. I’m not going to let them win.”

At the Indianapolis International Airport on Tuesday, TSA agent Wendell Hart stood guard at the Concourse B security checkpoint with his bomb-sniffing black Labrador retriever, Howard. An airport police officer patrolled the food court on a Segway. A sign advised travelers: “TSA K-9 teams in use. Please do not pet dogs.” TSA spokesman Mark Howell said the dogs are regularly assigned to Indianapolis on rotation. The TSA expected to screen 75,000 passengers in Indianapolis from Wednesday through Sunday, Howell said.

Each year, more than 7 million passengers use the airport, which averages 140 daily flights.  Tuesday afternoon, passengers moved quickly through security checkpoints. Ted Deptulski, 72, who flew to Indianapolis from Newark Liberty International Airport in New Jersey, said getting through security there was swift, as well. “It was normal as could be,” said Deptulski, who flies about three times a year. “Everything worked out perfectly. No delays.”

Deptulski, who was visiting family in Bloomington, Ind., said he was aware of the State Department’s global travel advisory issued Monday and was ready to do his part spotting suspicious activity. “I do look a little more closely at people, and if I see something that is off, I will not hesitate to report it,” the Flemington, N.J., resident said.

Donald Conner, who flew to Indianapolis from the Rick Husband Amarillo International Airport, said TSA agents in Texas removed his toothpaste and deodorant from his carry-on luggage to inspect it. “That’s something that never happened before, but it didn’t upset me,” Conner, 27, said. “I agree with it.”

Contributing: John Tuohy, The Indianapolis Star