The TSA reports that in 2020, they found guns carried by US air passengers at twice the rate they did in 2019. To put some context around that though, the found 10 guns per million passengers last year, compared to 5 guns per million passengers in 2019. The most guns turned up at Hartsfield-Jackson Atlanta International Airport (ATL) followed by Dallas/Fort Worth International Airport (DFW) and Houston's George Bush Intercontinental Airport (IAH). From a TSA report:
TSA officers discovered a total of 3,257 firearms on passengers or in their carry-on bags at checkpoints, although total passengers screened in 2020 fell by 500 million versus 2019 due to the pandemic. Of those firearms caught in 2020, about 83 percent were loaded. In 2019, TSA officers stopped a record 4,432 firearms, of which 87 percent were loaded.
Passengers with firearms at checkpoints were stopped at 234 airports nationwide.