I could definitely see that happened in the Postwar United America especially with Midwestern cites, towns and countryside got destroyed by the Two Great Wars. The Midwestern would be an chance of Mass exodus to migrated other States like Pacific and former Canadian provinces specifically Ontario to be settled on Mass.One thought I've had for the Post SGW era was the US flooding Canada and the former CSA with "Homestead Carpetbaggers." With most of them actually being from Eastern Europe and Asia who either took up the opportunity or were part of some deal between the US and their parent nations. Mixed with awarding land grants to US military vets and their families...
While Germany wanting to hold onto their overseas colonies and stabilize the Balkans. Decided to deport many ethno-national groups from Eastern-Central Europe to Africa and further abroad with them becoming grudgingly loyal to Germany out of protection.
Their highly chance Immigrated will came from Central and Eastern Europe country ( I bet that most will come from Austria Hungary) will make to Traveling to the US specifically in Midwest where Most Euro influence the most will have in the States, so there will be More Czech, Polish, Hungarian and Serbs community on the cities of Midwest.
Asia will not have More immigration to USA because of Most of them will be control by the Japanese from Tokyo meaning that they will highly be only served to Japanese immigrated and No immigrant to USA