All of the comments about leaving foods behind are right on. Don't carry any food stuffs. You 'can' have meat, but no pork or lamb. No veggies. No fruits. If you have a pet...leave that food behind, unless it is in it's original container and was made in the US too. Replenish once you have crossed. Even garlic and/onions. Don't.
Thus is not onerous...just leave it at home and cross empty. It truly does make is so much easier. And they still may board. It doesn't take long. As long as you are playing by the rules. I cross almost weekly and sometimes I get a more thorough check than others..but that is just the way it is.
Hints? Everyone take off sunglasses before you get to the agent and shut down the engine soon as you can. Don't fret about being all single answer, one worded...be yourself.
Same applies for coming back into Canada. No fresh fruits or veggies. I bring back meat and if in the US for 48hrs, I bring in my Duty Free alcohol. Whatever you buy...keep the receipts.
It is a PIA but the border is serious business both ways.
Gary Haupt
BC