I see the process but what's the goal?
The goal is to prevent accelerating divergence of two regional sub-economies in which the stronger sub-economy enjoys the GDP-boosting effects of a slightly under-valued currency and the weaker one suffers from the GDP-sapping effects of what for that region is an over-valued currency.
I am sure such disparities are also seen in the states off the USA? Oregon and Maine, for example to take two random examples.
There are disparities, of course. Some of the disparities are handled by differences in the balance of tax collect and benefit payments across states. And some of it is handled by state-to-state migration. On an annual basis, about 3% of the US population moves to a different state. IIRC, New Jersey and New York are the biggest net losers and Oregon and California are the biggest net gainers. Some cities have shrunk significantly: Detroit has about 1/3 the population it had during peak auto-making days.