Green Card
To stay permanently in the US, you must apply for a green card which gives you all the rights of a citizen (except to vote).
It can be obtained by way of family ( as husband/wife, parent, child, brother/sister of American citizens ) with a minimum age of 21, or by way of a company if you are the manager of a company settled in theUSA, an artist, a professor, a well-known sportsman or scientist ¡K or by way of the Lottery which delivers 55 000 green cards in irregular intervals and by drawing of lots with a 100$ contribution (please note there are conditions that apply).
info taken from http://www.easyexpat.com/