Accounts generally have a daily withdrawal limit at ATMs. If you're traveling with $18,000 in cash, that's probably well above what you can withdraw from an ATM

Accounts generally have a daily withdrawal limit at ATMs. If you're traveling with $18,000 in cash, that's probably well above what you can withdraw from an ATM in a day. I think a lot of accounts have ATM limits of $300-1,000 per day. I'm sure there are ones that are higher and I think a lot of banks let you request a higher limit, but I think it's probably more than just a paper trail. Personally, I'd never travel with that much cash, but I could see withdrawing that amount of cash having potential road blocks if your bank doesn't exist in the state you're traveling to.