How immigration/emigration work?
Is it closed system - that is total emigration and immigration from all countries are equal?
Or people appear and disappear into thin air?
I'm absolutely sure they do disappear and appear into thin air from all the testing I've done. Otherwise numbers just wouldn't add up. Every country's immigration/emigration level is calculated separately, independently from other countries so naturally countries are not related. This is sad but you get what you get. This was done much better in Victoria 2 game where immigration and emigration was actual people leaving and coming to a country so you could see some interesting developments, especially in the New World, where your countrymen would begin to live, even if by a few percent sometime, which is exactly how USA was built. But even in Europe for example population movement was rather realistic so you would have more cultural intermixing in border regions for example but very little inlands and it would all depend on various reasons.
sounds like an evil idea for a real addon : Supreme Ruler Refugee - now you can watch the population red hex filter moving in realtime...
Maybe its just statistically simulated on a per region level - last time i ruled earth (in SR2020) i had 200.000 people moving out and in.
I don not know yet if it is still there or was removed to gain a few cpu-seconds for 3d...
my mods viewtopic.php?f=79&t=25932
(even techs and units for everyone - AI will own you too)viewtopic.php?f=87&t=26151