Registered Nurses (RN's) are classified by the U.S. Department of Labor as a Schedule A shortage occupation, which makes it easier for RN's to immigrate to the United States than persons in other occupations. This also means that they get their green cards faster than their counterparts in other professions.
The key is that the foreign RN must be petitioned by a U.S. employer in order to immigrate to the United States. The initial step in a Schedule A case is to file a Form I-140 application package and appropriate supporting documentation to the appropriate USCIS service center.
Hiring a skillful and reputable immigration lawyer to assist with the process is critical to a fruitful outcome without unnecessary processing delays.