Under rules by the US Transit Security Administration (TSA), you can still lock your luggage — it won’t be turned away if comes locked to the airport — but there is a slight hitch. If you luggage is locked with a lock that the TSA can’t open, they may very well cut it off to inspect the interior of your bags. There is a way around this, and it’s a very simple one to pursue if you would like to make sure that you not only maintain the security of your luggage, but also arrive at the end of your trip with your locks intact.
In order to still lock luggage when you fly, you need to purchase locks certified by the TSA. In regular stores, these will often come with a little flame logo, but most also state that they are TSA certified. Each of these special locks can be opened with TSA keys. If inspectors want to open a piece of baggage, they just use their skeleton key to open the lock and look. That way, they don’t have to mess with cutting off the locks.