I'm the type of person that gets fascinated by facts so I am going to present you to a link that has facts about green cards and permanent residency from the Law Office of Jeffrey O'Brian http://www.obrienimmigration.com/green-cards/ . Something interesting is that an immigrant can marry a United States citizen and get citizen their self if they meet the requirements. Maybe that explains why I had a family friend trying to marry me to her daughter on my last trip out of country?