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In his blog for The Atlantic magazine, James Fallows claimed that Eastport, ME was the easternmost point in the US. A writer commented that no, the easternmost point in the US was somewhere in Alaska, as Alaska crosses the 180th meridian. Another correspondent (me) wrote that this was silly - that the easternmost point of a landmass is the extreme point of the landmass that can be reached by traveling in an easterly direction, or more precisely, the last point on the country found by sweeping a line of longitude in an easterly direction. (This is more complicated for countries that don't have contiguous territory, but for now let's assume the territory is contiguous (and yes, I know that Alaska borders Canada and not another US state)).

Is there any convention in the geography community that establishes the meaning of "easternmost", preferably one that can be cited?

  • What about the Amundsen-Scott base on the South Pole? – mdsumner Mar 3 '14 at 5:26
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    I'm getting stuck in an eastern paradox. I read the article and I agree with both points of view. – Fezter Mar 3 '14 at 6:49
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    I think it may be best to think of it in a simple way: "the sun rises in the east and sets in the west". Therefore, I would say that the easternmost point in the US is in Maine. – Craig Mar 3 '14 at 16:59
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    @Fezter There really is no paradox here and it's ok to agree with both points of view. One definition (Llaves) is intrinsic in the sense that (a) it depends only on the set of points considered to constitute the US and (b) does not rely on a choice of coordinate system; whereas another definition (the commenter) is artificial in the sense that it depends on the coordinate system. Which definition is appropriate depends on whether you are trying to characterize properties of part of the earth's surface or merely characterize how it is described in a particular coordinate system. – whuber Mar 4 '14 at 17:00
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    As always, a great comment/answer from whuber. However, the original question remains "what does easternmost mean when used by a geographer?". I believe whuber's last sentence exactly hits the point. If someone asks you "what is the easternmost point in the US", they are asking you "to characterize properties of part of the earth's surface", the notion being that you cannot travel farther east and remain in the US, or equivalently as #Craig's comment implies, where does the sun first rise in the US. – Llaves Mar 4 '14 at 22:28
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North, east, south and west are directions relative to “something”. The two things you are taking about are:

  1. easternmost point in a (mulitpart) polygon: easternmost point in the US
  2. a coordinate system to measure geographic latitude and longitude: measured angle in direction (east/west) relativ to Greenwich

If you do not mix these two things, I can't see no problem.

The eastmost point in the blue polygon is marked with a red point. We are talking about a position relative to the polygon. We to not talk about a position relative to Greenwich. We even do not know whether the point is located east or west of Greenwich. And it is regardless of where prime meridian is defined. Even if the prime meridian is not defined in Greenwich but in Berlin, Moscow or Tokyo: The red point is still the eastmost point of our blue polygon. enter image description here

Let us now replace the blue polygon by the area of USA. Maine is the easternmost point in USA: enter image description here

If we use a GIS and want to ask “where is the easternmost point of USA” we must not ask: “Where is the maximum x coordinate (in eastern direction) measured in a geographic coordinate system where prime meridian is set to Greenwich?”. The answer of the second question will be “Aleutians” (180 degree) .

  • It gets less obvious if the country in question spans more than 180 degrees and it isn't a single polygon. If there are any such countries. – Uffe Kousgaard Mar 4 '14 at 14:09
  • This is precisely my argument. As to #UffeKousgaard's comment, I'm pretty sure no country spans more the 180 degrees, whether one polygon or not, at least if we exclude unincorporated territories. – Llaves Mar 4 '14 at 22:22
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North, east, south and west are directions so the eastern most point depends on the observers location and therefore I don't think you can define an absolute eastern most point since it will change depending on the observer

  • great point. A good example would be any map centered over Africa instead of the USA. In that case, Alaska looks more eastern than Maine... – Craig Mar 3 '14 at 21:52
  • This is exactly the basis of my argument for making Maine the easternmost point. Unless you want to allow any point to be the answer by virtue of picking an appropriate observation point, the logical place to put the observer is within the boundaries of the country. And any point more than 180° east of the observer is considered west. – Llaves Mar 3 '14 at 23:16
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The most Eastern point is Maine, since you would have to travel towards the (North)West in order to get to Alaska.

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Why not let the International Date Line separate east from west? Siberia's Chukotka Peninsula and the Aleutians both cross the 180th meridians but not the IDL. It makes no more sense to call the furthest Aleutians the U.S.' easternmost point than to call Little Diomede Island Russia's westernmost.

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The easternmost point in the US is technically a point in Alaska's Aleutian Islands, since it lies just west of the International Date Line. Agreed that the Eastern most point of a landmass should be determined by sweeping across its latitude in an easterly direction (as you suggest) but the question asks about the United States, not the North American landmass--meaning there is no choice but to include islands and datelines in the calculation.

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    The Aleutians do not cross the International Date Line, but they do lie across the 180th meridian. – Llaves Mar 4 '14 at 23:12
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It seems that we are mostly agreed that the question is open to interpretation. I'd like to bring up what I believe to be the real issue:

It is not a practical question to ask -- it is a philosophical one. It should be asked in quizzes, for light entertainment.

Both the question and answer ought to depend on how "tricky" is the quiz -- or for whom it is intended. Either way, the question should be unambiguous (unless the correct answer is "it depends...").

I first heard the question (about 25 years ago) in a very fun and interesting geography quiz board game whose name I forget. It was worded something like this: Which US State has the most Easterly longitude. Answer: Alaska.

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The International date line was modified to place the Aleutian Islands east of it. However, Attu Island, scene of a WW2 Battle, is located just to the west of the IDL, making it the furthest point EAST of the United States.

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