Just a very short answer (I'm at work): West Germany, south and than north. why?
Sorry, everyone here has their own pet theory of what led to the increased incidence of MS in modern society and I'm one who believes in the hygiene hypothesis.
Additionally, it seems the evidence shows that the first generations meeting MS succeptibility criteria experience more agressive and optically oriented MS, hence the recent perception (mis-conception) that blacks/asians/american indians are genetically predisposed to more virulent versions of MS.
In fact, I'm convinced that I read earlier articles telling that in the early 20th century MS was more often optically oriented and aggressive in American whites, although Dr Kurtzke tells me he doesn't remember that being the case.
To get to the point, with the elimination of the Berlin wall recently it's hopeful that the East German population has begun to experience similar wealth to the rest of Germany, but according to the hygiene hypothesis, at some point in the near future we're going to see a drastic rise in allergies, asthma and autoimmune diseases also in that population...in essence the "MS map of geographic incidence" will add another degree of fuzziness in adding East Germany to the areas of higher incidence http://www.pbs.org/wgbh/evolution/libra ... 04_07.html
You might wonder what an article about allergy and asthma incidence has to do with MS but by leaps and bounds it's proving out that allergies/asthma/autoimmune diseases/autisms and some cancers drastically increased incidence at the same times/places/conditions and that they continue to be unheard of or rare in vast areas of the world today.
What we all need to be wondering is "why do I need to be saddled with MS when vast areas of the world don't experience it?" and "why don't vast areas of the world experience MS so that we in the "developed populations" can adapt that aspect?"