Also, that would be about 37% of the US economy. California making the highest percentage at 14% of the US economy while New York would be in 2nd place at 8%. The least impactful would be Vermont with 0.2% (for got to include Rhode Island). However, I think this would wreck the world economy with the financial hub of the US (New York City) who manages the investments of world's reserve currency (dollar) would switch from US Dollar to Canadian Dollar. The US would also lose access to the Pacific and a considerable amount of military force stationed in the West Coast states.
Not to mention half of the important US ports. The states left would face a harsh reality when everything tripled in price as all the goods that used to be subsidized by the rich states are now hit with import taxes as well.