Which two countries share the longest international border?

Which two countries share the longest international border?
Photo by Greg Bulla / Unsplash

If you have been watching the news, you likely know about the controversy surrounding the U.S.-Mexico border, however borders are much more important that that.

Borders are established through warfare, colonization, or simple symbiotic agreements between the political entities that reside in those areas; the creation of these agreements is called boundary delimitation. Do you know which border is the longest?