Importing Car, Crossing Border on Old US Plates

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I am wondering if there are going to be any problems driving my car--with the current U.S. registration plates and U.S. insurance--back and forth across the border as I move my things to my new home.

It will take some time to get the RIV papers and get the car inspected and registered and I am wondering if I am going to have any problems driving it with the US plates during that time. I am moving to Manitoba and MPI says you can drive your car on the old plates for up to 3 months.

Canada Border Services gave me an ambiguous answer and US customs and Border protection acted like it was a silly question.

Thanks!