49th parallel 

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.

49th parallel by Eugene206 December 8, 2006

49th parallel 

For something that's similar, yet has a defining distinction (for example, the 49th parallel separates the identical US and Canada)

They used to have everything in common, now they're on the 49th parallel.

49th parallel by jhkjhkjkjh May 1, 2022

49th parallel 

Can either mean a part of the Canada-USA border (as it follows the 49th parallel north for a part of the border) or the 49th parallel north or south (circles of latitude).

1: I live in Seattle, near the 49th parallel. I travel to Vancouver every Saturday evening.
2: There are so many circles of latitude, but the 49th parallel north/south just stands out to me. It's my favorite.

49th parallel by what pseudonym do i use October 22, 2023