Over $10 grand has to be declared. The problem is that some American cops/border scum take the carrying of any amount of cash over $100 or so as "possible drug money" and use it as license to steal it. Especially if their victim is of the wrong color, creed, or ethnicity.

It's a shame that the US is too filled with fearful idiots to go back to the virtually open pre-9/11 border with Canada.