Slang reference for the border between the United States and Canada. The 49th parallel of latitude does make up the western third of the U.S. - Canada border (the border dips south through the Great Lakes region), but the term refers to the entire border, referring to both the geographic and cultural divide between the two countries. Although scrutiny is understandably higher since 9/11, the border is still probably the most open international border in the world.
The 49th parallel is the longest undefended border in the world.
by Eugene206 December 07, 2006