There are two main ways of immigrating to the US with a US citizen partner if you reside outside the United States:
A fiancé visa: If you haven’t married your partner yet, a fiancé visa issued at a US embassy or consulate overseas will allow you to enter the US. You will then have 90 days to marry your partner. If you do so within 90 days and apply for a green car based on marriage, you can remain in the US while you are waiting for your petition to be adjudicated. If you fail to marry within 90 days, you will be expected to depart the US immediately. Remember that a fiancé visa has nothing to offer you if you already live in the US.
An Immigrant Visa: If you are residing outside the United States and you cannot apply for a green card through marriage in the United States, you may apply for an Immigrant Visa at the US consulate in your home country. After entering the United States on an Immigrant Visa, the USCIS will mail your green card to your address in the United States.
