Green card

Since your girlfriend has not yet immigrated to the States, you may be able to marry and go to the green card interview together. I note that the late stage of your marriage may cause some concern to a consular officer as to whether it is bona fide or whether it is merely a marriage of convenience to get you your green card. A large concern may also be the timing since the processing must be complete and visa lottery winners enter the US by September 30th. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.

After she gets a green card, she can petition for you to become a permanent resident too, but you will have to wait for an immigrant visa number, which can take many years.  In the mean time, if you are married to a lawful permanent resident, you will no longer be able to enter the US in a non-immigrant status.