When flying domestically within the USA, there is no limit to the amount of cash that you can carry or have to declare. However, if you are found flying with large amounts of cash or money, TSA officers may question you as to why you have it and details of your trip.
Can you carry cash in your pocket through airport security UK?
There are no legal limits on how much cash you can travel with but, if you are flying, airport security can take action on amounts up to £10,000 if they deem it suspicious.