in general the periphery of the country has less immigrants.

in general every medium/small city will have an area of economic depression, but many medium or small cities someone had a reason to do tourism to have some comfy areas too. the economic depression parts are present regardless of immigration demographics - every town has a "high street" but they cannot sustain businesses beyond mcdonalds, pound shop, pharmacy, charity shops.
every town will have a little crew of drug addicts that camp out at one of the closed down high street storefronts and enjoy their social life