[David]

Hopefully someone chimes in with more experience than me but here's mine. I drove into Canada several years ago to inspect a piece of equipment we were buying in Toronto. I had no paperwork on me besides my passport and that was big mistake. I tried to explain that we were spending $300k on a new product from Canada but that didn't help much. After about 30 minutes they let me through but they made it sound like it wasn't going to happen. So I'd take all the paperwork you can.

Driving back into the US: Me "Do you need to see any paperwork?" US Border patrol: "No, go on through."