Security lines Monday at the hub were an hour to 90 minutes, causing many flyers to miss their flights. This comes after reports Sunday that a traveler carrying a firearm managed to board flight there earlier last month.

The passenger with the firearm eventually reported it to the airline, saying they had forgotten the weapon was in their carry-on luggage. There was no flight delay or other incident arising from the mistake.

The troubles at Atlanta are magnified because of the airport’s prominence. Hartsfield-Jackson has ranked as the world’s busiest airport since 2000. At least six security lines were closed Monday, traditionally the busiest travel day.

As the shutdown drags on, more TSA employees nationwide are calling in sick or not coming to work. On Monday, TSA had an unscheduled absence rate of 7.6%, more than double the amount from a year ago.

Atlanta is hardly alone. Last Friday, Miami International Airport closed security checkpoints at one of its six terminals for three afternoons due to a shortage of TSA screeners. After 1 p.m., Monday, all restaurants and shops in those terminals will be closed, after being shuttered Saturday and Sunday afternoons.

And on Monday, Washington’s Dulles International Airport closed some security checkpoints after a notable number of TSA employees did not show up for work.

An estimated 51,000 TSA officers are currently working without pay because of the shutdown. That represents more than 6% of all government employees being ordered to do so.

The TSA, however, is downplaying the impact.

“As the current lapse in funding persists, TSA officers continue to perform with the utmost professionalism and dedication,” TSA spokesman Michael Bilello said last week. “We thank TSA officers for their resilience and diligence, and we thank industry and the public for their continued acts of kindness and support.”