One of the most common ways to obtain a green card is through marriage to a US citizen. This is sometimes referred to as a green card marriage.
Now before continuing, it�s important to recognize that you can also obtain a green card through marriage to a Lawful Permanent Resident, that is, someone holding a green card. But right now we�re talking about obtaining a green card through marriage to a US citizen � we�ll be talking about obtaining green cards by marriage to a LAWFUL PERMANENT RESIDENT.

A Green Card Marriage is one in which an alien marries a US citizen and thereby becomes eligible to obtain lawful permanent residence in the U.S., that is, a green card. This is completely legal and is provided for by Congress.
So long as you get married for traditional reasons such as love and affection, it�s perfectly OK that your �green card marriage� results in an immigration benefit to you. The only time this poses a problem is where someone enters into a fake marriage or �sham marriage� that is designed solely for the purpose of getting an immigration benefit If you fall in love, get married, and now want to apply for a green card, that�s great. Congress welcomes you and your legitimate �green card marriage� based on your love and affection for one another. The green card marriage�when not a sham�is a wonderful thing.