5 ms·

Hm. I feel like the french republic can still make the claim though, at least according to this wikipedia map. https://upload.wikimedia.org/wikipedia/commons/6

Hm. I feel like the french republic can still make the claim though, at least according to this wikipedia map. https://upload.wikimedia.org/wikipedia/commons/6/67/Mapadefrancia.svg https://upload.wikimedia.org/wikipedia/commons/6/67/Mapadefr...

wolvesechoes 1y ago
It is always funny to ask people what country has the longest land border with France.
- fakedang 1y ago
  For those wondering, it's Brazil.
  - crazygringo 1y ago
    > The Franco-Spanish border runs for 685.42 kilometres (425.90 mi) between southwestern France and northeastern Spain. [1] > The Brazil–France border is the line, located in the Amazon Rainforest, that limits the territories of Brazil and France. The border is located between the Brazilian state of Amapá and French Guiana. It is 730 kilometres (450 mi) in length. [2] I'll be damned! [1] https://en.wikipedia.org/wiki/France–Spain_border https://en.wikipedia.org/wiki/France–Spain_border [2] https://en.wikipedia.org/wiki/Brazil–France_border https://en.wikipedia.org/wiki/Brazil–France_border
    - schoen 1y ago
      Is there a standard for measuring borders for these purposes, in light of the coastline paradox? I don't mean to suggest that there's no sensible way to do it; I just wonder if people might be using inconsistent methods sometimes, leading to not-very-comparable estimates.
      - crazygringo 1y ago
        It's an excellent question. The Wikipedia citations don't actually lead to much, and there's no indication they use the same methodology. Best I can find is the CIA World Factbook [1] which lists France's border with Spain at 646 km (under "France" and "Spain", same value), and Brazil's border with French Guiana at 649 km (under "Brazil"). So, already a radical difference -- from a 45km difference to a 3km difference (just 0.5%). But there's more: > When available, official lengths published by national statistical agencies are used. Because surveying methods may differ, country border lengths reported by contiguous countries may differ. But there's no indication whether these particular measurements are made by the CIA using the same technique with maps of the same resolution... or, being so close to begin with, whether different resolutions would change the asnwer... or if these are official lengths derived using totally different and ultimately incomparable procedures. So maybe it's not so cut-and-dried that France's longest border is with Brazil...? [1] https://www.cia.gov/the-world-factbook/about/archives/2022/field/land-boundaries/ https://www.cia.gov/the-world-factbook/about/archives/2022/f...
        jojobas 1y ago
        [flagged]
        tomhow 1y ago
        Please don't do this here. If a comment seems unfit for HN, please flag it and email us at hn@ycombinator.com so we can have a look.
        bragr 1y ago
        When the measurement was taken is important too because any border based on natural features is in constant flux. A big storm could cause the Oyapock River to straighten or create new bends or both.
      - throwup238 1y ago
        Borders are not like coastlines because they’re abstract delineations, not physical things, even though they’re frequently defined using geographic features. In this case, the length of the border is dominated by the length of the thalweg of the Oyapock river. Using thalwegs is SOP in international law when using rivers as the natural border and the choice of river is due to treaties that are hundreds of years old.
- lugao 1y ago
  It's funny because you can't measure borders due to the coastline paradox.
  - wolvesechoes 1y ago
    Doesn't matter in this context.
  - jcattle 1y ago
    Eh. If you care about relative measurements it doesn't matter much. Pick a sensible resolution, stick with it, you got yourself a ranking.
    - heavenlyblue 1y ago
      It also makes sense to pick a resolution because coastline changes on an hourly basis (and minute-basis, for rivers during rainfall), so that these differences would not massively affect the measurement every single second
  - falcor84 1y ago
    I'm not aware of any 2 countries having their border be a natural coastline
    - retsibsi 1y ago
      Same principle applies to rivers, though, and there are lots of river borders.
      - falcor84 1y ago
        It isn't the same principle. Firstly, coastlines are more jagged because they are hit by waves perpendicularly, while rivers are shaped by water flowing along the banks, smoothing them. Secondly, the borders are typically defined by either the thalweg (greatest depth) or median line, either being smoother lines than the banks. Thirdly, river borders are then in practice defined by measuring the coordinates of particular sample points along the idealized line and then using straight lines or simple mathematical curves to connect these, forming a simple non-fractal boundary.
- Rexxar 1y ago
  The other funny thing is the land border with Netherlands ... in the Caribbean.
  - mihaic 1y ago
    It's pretty nice that EU agreements of free travel apply to it as well.
seszett 1y ago
I measured it a while ago (well, 11 years now) and both France and the UK made the cut[0]. France has much more margin though, IIRC no single territory becoming independent would make the sun set on France. [0]https://ssz.fr/sun-never-sets/ https://ssz.fr/sun-never-sets/
- madcaptenor 1y ago
  I'm glad someone did this, because for a moment I was thinking that I was going to have to do the math on France.
- arethuza 1y ago
  France also has the longest internal scheduled flight - 9,349km https://en.wikipedia.org/wiki/World%27s_longest_domestic_flight https://en.wikipedia.org/wiki/World%27s_longest_domestic_fli...
  - diggan 1y ago
    Had*, seems it was added to work around American Covid restrictions, and it was only active for ~1 month.
    - seszett 1y ago
      You're thinking of the (temporary) Tahiti flight, but that was much longer than 9349 km. The person you're responding to was talking about the Paris-Réunion flight that has been active for a long time and still active today. I took it 15 years ago when I had to go to Réunion.
      - diggan 1y ago
        Oh, seems indeed I confused the two, thanks for the correction!

wolvesechoes 1y ago

It is always funny to ask people what country has the longest land border with France.

fakedang 1y ago
For those wondering, it's Brazil.
- crazygringo 1y ago
  > The Franco-Spanish border runs for 685.42 kilometres (425.90 mi) between southwestern France and northeastern Spain. [1] > The Brazil–France border is the line, located in the Amazon Rainforest, that limits the territories of Brazil and France. The border is located between the Brazilian state of Amapá and French Guiana. It is 730 kilometres (450 mi) in length. [2] I'll be damned! [1] https://en.wikipedia.org/wiki/France–Spain_border https://en.wikipedia.org/wiki/France–Spain_border [2] https://en.wikipedia.org/wiki/Brazil–France_border https://en.wikipedia.org/wiki/Brazil–France_border
  - schoen 1y ago
    Is there a standard for measuring borders for these purposes, in light of the coastline paradox? I don't mean to suggest that there's no sensible way to do it; I just wonder if people might be using inconsistent methods sometimes, leading to not-very-comparable estimates.
    - crazygringo 1y ago
      It's an excellent question. The Wikipedia citations don't actually lead to much, and there's no indication they use the same methodology. Best I can find is the CIA World Factbook [1] which lists France's border with Spain at 646 km (under "France" and "Spain", same value), and Brazil's border with French Guiana at 649 km (under "Brazil"). So, already a radical difference -- from a 45km difference to a 3km difference (just 0.5%). But there's more: > When available, official lengths published by national statistical agencies are used. Because surveying methods may differ, country border lengths reported by contiguous countries may differ. But there's no indication whether these particular measurements are made by the CIA using the same technique with maps of the same resolution... or, being so close to begin with, whether different resolutions would change the asnwer... or if these are official lengths derived using totally different and ultimately incomparable procedures. So maybe it's not so cut-and-dried that France's longest border is with Brazil...? [1] https://www.cia.gov/the-world-factbook/about/archives/2022/field/land-boundaries/ https://www.cia.gov/the-world-factbook/about/archives/2022/f...
      - jojobas 1y ago
        [flagged]
        tomhow 1y ago
        Please don't do this here. If a comment seems unfit for HN, please flag it and email us at hn@ycombinator.com so we can have a look.
      - bragr 1y ago
        When the measurement was taken is important too because any border based on natural features is in constant flux. A big storm could cause the Oyapock River to straighten or create new bends or both.
    - throwup238 1y ago
      Borders are not like coastlines because they’re abstract delineations, not physical things, even though they’re frequently defined using geographic features. In this case, the length of the border is dominated by the length of the thalweg of the Oyapock river. Using thalwegs is SOP in international law when using rivers as the natural border and the choice of river is due to treaties that are hundreds of years old.
lugao 1y ago
It's funny because you can't measure borders due to the coastline paradox.
- wolvesechoes 1y ago
  Doesn't matter in this context.
- jcattle 1y ago
  Eh. If you care about relative measurements it doesn't matter much. Pick a sensible resolution, stick with it, you got yourself a ranking.
  - heavenlyblue 1y ago
    It also makes sense to pick a resolution because coastline changes on an hourly basis (and minute-basis, for rivers during rainfall), so that these differences would not massively affect the measurement every single second
- falcor84 1y ago
  I'm not aware of any 2 countries having their border be a natural coastline
  - retsibsi 1y ago
    Same principle applies to rivers, though, and there are lots of river borders.
    - falcor84 1y ago
      It isn't the same principle. Firstly, coastlines are more jagged because they are hit by waves perpendicularly, while rivers are shaped by water flowing along the banks, smoothing them. Secondly, the borders are typically defined by either the thalweg (greatest depth) or median line, either being smoother lines than the banks. Thirdly, river borders are then in practice defined by measuring the coordinates of particular sample points along the idealized line and then using straight lines or simple mathematical curves to connect these, forming a simple non-fractal boundary.
Rexxar 1y ago
The other funny thing is the land border with Netherlands ... in the Caribbean.
- mihaic 1y ago
  It's pretty nice that EU agreements of free travel apply to it as well.

seszett 1y ago

I measured it a while ago (well, 11 years now) and both France and the UK made the cut[0]. France has much more margin though, IIRC no single territory becoming independent would make the sun set on France. [0]https://ssz.fr/sun-never-sets/ https://ssz.fr/sun-never-sets/

madcaptenor 1y ago
I'm glad someone did this, because for a moment I was thinking that I was going to have to do the math on France.
arethuza 1y ago
France also has the longest internal scheduled flight - 9,349km https://en.wikipedia.org/wiki/World%27s_longest_domestic_flight https://en.wikipedia.org/wiki/World%27s_longest_domestic_fli...
- diggan 1y ago
  Had*, seems it was added to work around American Covid restrictions, and it was only active for ~1 month.
  - seszett 1y ago
    You're thinking of the (temporary) Tahiti flight, but that was much longer than 9349 km. The person you're responding to was talking about the Paris-Réunion flight that has been active for a long time and still active today. I took it 15 years ago when I had to go to Réunion.
    - diggan 1y ago
      Oh, seems indeed I confused the two, thanks for the correction!