You do realize intra-country migration has the same effect right? In the US, the majority of counties are losing population, because people are moving to cities

You do realize intra-country migration has the same effect right? In the US, the majority of counties are losing population, because people are moving to cities. You're advocating for internal passports and residency permits: https://en.wikipedia.org/wiki/Hukou https://en.wikipedia.org/wiki/Hukou