Overview: Applying for a Green Card without an Employer Sponsor
For the majority of foreign nationals, there are two main categories of options when seeking a green card: family-based and employment-based. For individuals who do not have an immediate family member who is a U.S. citizen or Legal Permanent Resident, family-based options are either impossible or come with a many years-long wait.
Employment-based options can be further broken down into two categories: employer-sponsored and non-employer-sponsored (also referred to as self-petitions). Employer-sponsored options are the more common of the two; they include the Labor Certification process, which is applicable for all jobs, and Outstanding Researcher/Professor (EB-1B), which is only applicable for tenure track or permanent faculty or research positions. The only two employment-based immigrant visa categories where a foreign national may self-petition are National Interest Waiver (EB-2) and Extraordinary Ability (EB-1).
Many employers have limits as to who and when they will sponsor for permanent residence. They may only provide sponsorship for certain positions, or employees who will be in a position for more than a specified length of time. Alternatively, an employer may have a "waiting period" in which employees are not eligible for sponsorship until they have been with the company or institution for a certain length of time on a temporary visa.
Positions that are temporary by nature (such as postdocs, medical residents/fellows, or visiting faculty) or part-time will not be appropriate for employer-sponsored categories.
If you are investigating permanent residence categories that do not require employer sponsorship (i.e. ‘self-petitions’), note that your opportunities and qualifications for these categories will improve as your career moves forward.