To answer the question of any countries we do not allow people to immigrate to us from...yes, there are some, but I believe the criteria is based on your reason for wanting to come to America and how you are going to support yourself and/or your family, not necessarily your nationality. Furthermore, in some cases, if you wish to become an American citizen, you must be in America for 5 years before you are allowed to get your citizenship. So, if you leave to go back to your home country for 6 months, that 6 month timeframe is subtracted from your total. It is much easier for someone to get a visa to America if they have an American sponsor who takes responsibility for the immigrant...they aren't supposed to ask for welfare programs if they can't support themselves and if they get into legal, criminal trouble, the sponsor could be held accountable.
The paperwork a sponsor fills out from the INS is extensive and lengthy, and if they don't meet certain financial criteria, they have to find a co-sponsor, who is also responsible for the immigrant. Yes, I know from first-hand experience. Also, once the paperwork is filled out and all the supporting documentation (birth certificate, pay stubs, etc.) is sent to the INS it could take a long time (like over 2 years) to get approved. Then, the immigrant has a small window of time to get the visa from the American Embassy/Consulate in their country.
There are limitations the U.S. puts on some country's citizens for immigrating to the U.S. Like how many visas are allowed per year. And in some cases, the country the individual is leaving has moratoriums on how many people they will allow to leave. In some cases, the father is allowed to leave and come to the U.S., but the wife and children and other family members are made to stay in-country...kinda holding them hostage so the father will come back.
I'm all for immigration...but, there has to be limits placed and then the INS must follow-up with the immigrants to ensure the proper controls are in place. Knowing where the immigrant is and making sure they are contributing to American society positively.
