One word answer: Iceland
One sentence answer: Subject to the methodology and caveats below, with an estimated 2020 poulation center latitude of 64.336, Iceland has the northernmost population center among soverign nations, with Finland coming in second at 61.715, and Norway coming in third at 61.049
Methodology
- Using CIESIN gridded population data and national identifier grid at
https://sedac.ciesin.columbia.edu/data/sets/browse?facets=theme:population
under "UN WPP-Adjusted Population Count, v4.11 (2000, 2005, 2010, 2015, 2020)" and "National Identifier Grid, v4.11 (2010)" respectively, I wrote bc-pop-center.pl and bc-pop-center-parse.pl in https://github.com/barrycarter/bcapps/tree/master/COW/ to compute the national centers of population.
Highlights
If dependencies are counted as separate nations, the Svalbard and Jan Mayen Islands has the northernmost center of population at 78.596 latitude, with Greenland at 66.070 coming in second. Iceland is then third.
If dependencies are counted as separate nations, the Falkland Islands (Islas Malvinas) are southernmost at -58.083 latitude, but the other southernmost centers of population belong to sovereign nations.
The sovereign with the southernmost centers of population are New Zealand with -39.374 latitude, Uruguay with -34.073 latitude, and Chile with -34.059 latitude.
There are 933,120,000 gridpoints (of 30 arcseconds by 30 arcseconds each) of varying size total on the Earth. The Holy See of Vatican City covers only 1 of these gridpoints, whereas the Russian Federation covers 41,463,394 gridpoints. Because each gridpoint does not have the same area, it's a coincidence of sorts that these are also the smallest and largest countries by area.
Caveats
The national grid data treats dependencies as separate countries, so I used https://spreadsheets.google.com/ccc?key=pJpyPy-J5JSNhe7F_KxwiCA&hl=en (which geonames.org's countryInfo.txt file lists as being a source of dependent countries) to convert. This list does not appear to be complete, and my results reflect this. For example, New Caledonia is actually a dependency of France and Curacao is a dependency of the Netherlands. I briefly tried to add to the google spreadsheet, but only got as far as these two examples before giving up.
The line starting with FR/NL refers to Saint-Martin, which is apparently not sovereign, but co-owned by two nations. In theory, Andorra should be listed as "ES/FR" as it belongs to both Spain and France (for 6 months a year each), but I treat it as a separate entity.
According to geonames, Antarctica has a permanent population, but, since it is not owned by any nation (and since the gridded population data doesn't cover it), it does not appear in my results. If it did, it would by far have the southernmost center of population (at the Amundsen-Scott base, which is only a few hundred feet from the South Pole).
The national and population grid data is based on 30 arcsecond by 30 arcsecond grids, so the latitudes and longitudes are accurate only to 1/120 degree, so I give only three digits of precision above, though the files use full floating point precision, but, of course, the accuracy is still limited.
Other Notes
To Do
- I'd like to create an KML of these population centers just for fun.