Travel troubles continue to mount from the lingering government shutdown, with the TSA reporting a spike in worker call outs Monday.

Travelers in Atlanta were greeted with security line waits of more than an hour at Hartsfield-Jackson International Airport Monday, a busy day for business travel. At one point, six security lanes were closed, according to the Atlanta Journal Constitution.

Passengers took to social media to complain about the lines and warn other passengers to arrive at the airport hours before their flights.

At Houston Bush Intercontinental, the ticketing counter and security checkpoints at Terminal B, home to United airlines, were closed over the weekend due to security staffing concerns, and they remained closed Monday.

Flights are still departing from the terminal but passengers are being sent to Terminal C or Terminal E to check in and go through security. The airport says passengers can walk or take the Skyway tram to Terminal B to reach their gate.

Airport and city officials are advising travelers to "allow plenty of time for this change.''

Airports are trying to get ahead of TSA staffing issues related to the shutdown as TSA union officials predict an increasing number of agents working without pay will call out or quit. Miami was among the first, closing one of its terminals early over the weekend. Miami's checkpoint operations returned to normal Monday.

The rate of no shows by TSA employees on Monday was more than double the rate of a year ago, TSA spokesman Michael Bilello said on Twitter. Nationally, the percentage of unscheduled absences was 7.6 percent, compared with 3.2 percent on Monday, January 15, 2018.

Sen. Christopher Coons, D-Del., told reporters Monday that he is concerned about tens of thousands of federal law enforcement working without paychecks and hundreds of thousands of workers furloughed.

“Today is the first day that I’m getting unsolicited texts and calls from Delawareans who are traveling and are really struck at the delay and uncertainty around TSA, FAA and aviation security,” Coons said. “This shutdown has gone on far too long.”

Contributing: Bart Jansen, USA TODAY