/ Few economies are more closely intertwined than those of Canada and the U.S. Canada sends fully 77% of its exports to the U.S., while America puts Canadian addresses on 21% of its shipments. Now that tight and sometimes tumultuous relationship stands to become even tighter, thanks to the historic new trade pact between the two nations.
The hard-won agreement, worked out over 16 months of arduous negotiations and an intense last-minute push to meet an Oct. 4 deadline imposed by Washington, aims at creating nothing less than the world's largest open market. If the tentative accord wins the approval of...