Your US insurance should work in Canada up to 60 days.  I did the same.  The Canadian border does not ask you for insurance (at least they didn't asked me).  Make sure you get a stamp on your title (not registration) from the US side before you cross the border.  I think you need to make an appointment for that.  Also, remember that you cannot bring the financed car in Canada until it is fully paid off.  Check the link below.  It might be helpful to you.

http://www.riv.ca/importingavehicle.aspx

http://www.tc.gc.ca/eng/roadsafety/safevehicles-importation-usa-index-445.htm