What is the northernmost country that borders the US to the South?

What is the northernmost country that borders the contiguous US to the South?

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    $\begingroup$ I think this may be off-topic because it's a trivia question, not a puzzle / riddle / brainteaser / etc. $\endgroup$ Jan 19, 2015 at 10:20
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    $\begingroup$ I think trivia questions, when the responder doesn't know the answer, are answered with an "I don't know": "What's the capital of Estonia?" "I don't know". This question, however, is almost always answered with haste and complete certitude. The puzzle is in stopping, thinking and considering why such a simple question is being asked. Of course, for non-Americans, this may be completely different. $\endgroup$
    – mahboudz
    Jan 20, 2015 at 6:34
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    $\begingroup$ http://xkcd.com/169/ $\endgroup$
    – xnor
    Jan 21, 2015 at 4:07

5 Answers 5


The first part of the question has already been answered correctly by @Callidus, however the second has not. To answer the second part of the question:

What is the northernmost country that borders the contiguous US to the South?

The answer is again Canada: in Windsor, Ontario, which is south of Detroit, Michigan. That's the 2nd trick.


@Michael has correctly answered the riddle. At the risk of being pedantic, here are a few other points of interest:

Point Roberts, WA north of Saturna Island, BC


Niagara Falls, NY north of Niagara Falls, ON


Vanceboro, ME north of St. James, NB

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    $\begingroup$ One could argue that Point Roberts is not contiguous. $\endgroup$ Apr 8, 2016 at 17:40
  • $\begingroup$ Good call! I have been out-pedandic'd! $\endgroup$
    – Seth
    Apr 8, 2016 at 17:45

Well, the question could be interpreted as "Which country has the northernmost border which can be crossed from the US going south" or "Which country can be crossed into from the US going south has the northernmost extent.", "Which country can be crossed into from the US going south has the northernmost southern extent.", "Which country can be crossed into from the US going south has the northernmost centroid."

The question is further complicated by whether marine boundaries count for adjacency and extent and how to handle disputed claims.

It looks like any way you work it out though, the answer is Canada.

Allowing for a disputed marine border, the northernmost section of US border where the US is to the north is the Alaska-Yukon border in the Barents Sea according to the US claim that the border bends to be perpendicular to the coastline. The Canadian claim is that the border continues due north-south.

For an undisputed land border, there's a short section near the south end of the Alaska-Yukon border between Mount Hubbard and Mount Seattle where Alaska is to the northwest and the Yukon is to the southeast.

The US shares land borders with Canada and Mexico, and also has a marine border with Russia, but that border never has the US to the north. The Marine border between the US Virgin Islands and British Virgin islands also has a short section where the US is to the north. Even if marine borders count this leaves the question of whether overseas territories count.

Even if we include the United Kingdom with all of its overseas territories, the northernmost point in the Shetland Islands is still much further south than Canada's northernmost point on Ellesmere Island. Canada also has a more northern centroid and southernmost point than the United Kingdom with its territories.


Part 1:

Canada borders Alaska to the south, and is north of Mexico. That's the trick.

Part 2:

Mexico is the only country that borders the contiguous US to the south.

  • $\begingroup$ Part 2 is wrong. See Michael's answer. Remove the word "only" and you'll be correct. $\endgroup$ Jan 19, 2015 at 13:19

Assuming there's no trick here, a simple answer is



Mexico is the ONLY country that borders US to the south, therefore the most Northen of them all.

All in all, this isn't really a puzzle, just geography.

Extra information for hungry minds:

* Canada – borders US to the north.
* Mexico – borders US to the south.

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    $\begingroup$ I don't know why but that "Extra information for hungry minds" and the spoiler made me laugh out loud. $\endgroup$
    – Quark
    Jan 18, 2015 at 6:35
  • $\begingroup$ @Quark What's so funny about it? lol. $\endgroup$
    – warspyking
    Jan 18, 2015 at 10:31
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    $\begingroup$ It seems a bit naïve to assume there's no trick on a site that's all about puzzles and riddles and such. If there weren't a trick, this would be off topic as just a geography question. $\endgroup$
    – cHao
    Jan 18, 2015 at 13:48
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    $\begingroup$ @cHao Maybe the trick is that everyone expects a trick when there isn't one. $\endgroup$
    – jwodder
    Jan 18, 2015 at 18:33
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    $\begingroup$ @ir7 Can't speak for Spanish, but I can assure you that Mandarin is every bit as muddleable as English, in fact I think its regional variant situation is arguably worse than English's. $\endgroup$
    – March Ho
    Jan 27, 2015 at 7:19

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