Amounts much less than that trigger "structuring" meaning that trying to adhere to the law of not carrying more than $10,000 shows you're trying to skirt the law by not trying to break the law. Crazy! People have lost their money to seizing for carrying thousands less than the $10,000 trigger. Because government says you meant to break the law, even if you didn't.
Oh yeah. I’ve carried over $10k several times but I always had a paper trail to back it up.