I think we would find, if we investigated the facts behind this article -- and I'm just guessing, but it's an educated guess -- that the hardest hit counties in this respect would be the small, rural counties, particularly in the Great Plains and the Rocky Mountain regions. Counties in those regions have little to offer but ranching as a career, and ranching is going the same direction as the family farm in this country. There is no money in it, and the pressures to earn and live well are felt by the youth in those communities. Consequently, they are moving to the population centers to find a new life.
The Post gives misleading information in claiming that cities like New York, Chicago, and St. Louis, among others, would have lost population if not for foreign-born residents. There isn't an inner city in any major metro area in the country that isn't struggling with population loss, due to continuing, second-generational flight to the suburbs. So while it may be technically true that the central city in a metro area is losing population, I know for a fact the St. Louis metropolitan area as a whole has grown over the last 15 years, not through foreign-born residents but through natural-born and naturalized, successful American citizens relocating, particularly from the West Coast.
This article is nothing more than a badly disguised push to keep the borders open, quoting as it does from a couple sources hyping the value of foreign-born immigrants. I agree, as long as they are legal. However, given that most "foreign-born" residents are illegal, it is far more necessary to close the borders to illegal immigration, as illegals currently enter the country at more than 2-to-1 over the rate of legal immigration.
Epic fail, Huffington Post. Shame on you.