Drugs of all kinds flow quite freely back and forth across both borders to meet demand in all three countries. I hope you're not suggesting that the US is just an innocent bystander. How many guns cross our border illegally from the US? How many humans are trafficked? I don't think any US citizens have invaded canada but lots of illegals have come here through the US after being bussed to the border from the south. Again, there is regular flow back and forth across both borders because there is a network of people who benefit from that flow.