Can I fly with an airband receiver in the United States?
This is probably more a travel question than an aviation one, but I did some Googling of various aviation and travel sites and the consensus seems to be this:


You can carry the scanner with you, but if you're unlucky and encounter the wrong TSA agent on the wrong day then you may be asked a lot of questions at security (the TSA's "Can I Bring..." tool seems to consider scanners to be generic electronic items)
Using the scanner while sitting in the airport is fine, but if you attract attention to yourself then you may be questioned by the police or airport security
You may not use a two-way radio on board the aircraft, because they're specifically required to be off at all times (this is in every airline's safety instructions that I've seen); that shouldn't apply to a radio that only receives but the cabin crew might ask you to turn it off anyway if they're not sure about it
Even if you did operate the scanner in the air, the reception is terrible and you'll probably hear only the aircraft's crew, not ATC


Note that this information is for the USA only, many other countries are very strict about possession and use of scanners or two-way radios and in the UK (for example) just listening to ATC is actually illegal.