Can I get a green card if I marry a same-sex citizen of the United States?

In states where homosexuality is legalized, if you get a marriage certificate, you can get a green card.

One of the ways to obtain U.S. permanent resident status (i.e. green card) is indeed marriage to a U.S. citizen (commonly known as a marriage green card). It has nothing to do with the time you have lived in the United States (if you meet the conditions, usually how many years? You can get a green card in just a few months). The only requirement for a marriage green card is that your marriage is genuine and meets the conditions.

Second, regarding the issue of same-sex marriage, only a few states in the United States recognize the legality of same-sex marriage.