To the OP: You do realize that Canada is ALSO the U.S.'s biggest trading partner too right? This is hardly surprising gang, we do live right next door to each other on the same continent....
From the Office of the United States Trade Representative:
"Canada is currently our largest goods trading partner with $632 billion in total (two ways) goods trade during 2013. Goods exports totaled $300 billion; Goods imports totaled $332 billion. The U.S. goods trade deficit with Canada was $32 billion in 2013."
More on their website....
https://ustr.gov/countries-regions/americas/canada