Originally Posted by Pipecrew

Not fully related but if the amount is under 10k usually and on your person you won't have a problem.

However today when flying out of lax. I had 400 cash on me and I went through the 3d X-ray thingy. They made me step out and hand them my cash and then get back in. Never seen that procedure before. Every other time they encourage you to hold onto your cash and boarding pass