Nobody says you can't, carrying whatever amount across the border is perfectly legal. What's illegal is trying to carry >10k without declaring it to the customs

Nobody says you can't, carrying whatever amount across the border is perfectly legal. What's illegal is trying to carry >10k without declaring it to the customs. If you're a law abiding citizen, why wouldn't you declare it? If you don't, well congrats, you're no longer a law abiding citizen.