http://www.crainsdetroit.com/article/20140123/NEWS/140129933...
With 700,000 people living in a city that used to hold over two million there's plenty of room.
The specific visa requested is the EB-2, which basically requires a Masters or PhD as the credential needed to establish exceptional ability in a specific field.
Do you have to prove residency in Detroit? Do you have to work for a company in Detroit? What if you pick up and leave? Do you get deported? How would they even track that?
as opposed to where the United States NEEDS them. I think we should give out visas to Masters and PhDs and allow those people to go where they please. That way... we would get the best people as well... not just the most desperate.
What's the benefit to the country if a new worker from abroad replaces a current worker but at a lower wage if that means the person 'usurped' needs state assistance or becomes under-employed (and bumps someone else from work to benefit-reliance)? Sure business owners probably benefit but such benefit seems pretty localised.
How about if you let a lot of foreign workers come in who are well skilled and they flood a field in such a way that no students leaving college in that field can get a job. The incoming worker likely can accept lower wages which local [likely] debt-laden students can't. The field falls flat - the local population stop training in that field and you've either got a future skill crisis or a long-term reliance on immigrant workers.
If you want to preference native/endemic population over immigrants at all then I think you need to be very specific in the immigration you allow.