Under the new rules, passengers can carry on knives with folding blades no longer than about 2 1/3 inches -- that's 6 centimeters -- and blades no wider than half an inch.
Tt will still ban knives with blades that are fixed or lock into place, or that have molded handles.
Box cutters and razor blades will still be banned, too.
It's the first time since 9-11 that such carry-ons will be allowed.
"But what it will provide for TSA it will allow them to focus on the things that are a higher risk, going to the checkpoints and not waste their own time on things that are of low risk," says Wood County Regional Airport Manager Terry Moore.
This change will also bring the US in line with the International Security Standard---allowing knives with blades up to six centimeters.
It's expected to take effect April 25th.