If you get married to a US citizen, you can easily obtain a US Green Card. Initially you will be issued a two year conditional Green Card and later you will be permitted to file an application to remove conditions on that card and to obtain a ten year Green Card. But you need to meet few requirements and file the application to remove conditions along with your US citizen partner and you cannot file this form by yourself. Form I-751, Petition to Remove Conditions on Residence is the form that must be filed by you, at the end of the two year conditional period jointly with your spouse. The process of removing conditions on your card will be easy if you are still married to the same US citizen. But if you have been separated from your spouse, it may not be that easy for you to get the conditions removed and to get a ten year Green Card.
To remove conditions on your conditional Green Card, you need to file Form I-751 jointly with your spouse, three months ahead of the date of expiration of your card. However, you can still file an application to remove conditions on your card, if you are separated from your US citizen spouse. To get an unconditional permanent resident card even after divorce, you need to file a waiver of the joint filing requirement. You will be granted a waiver of this requirement, if you establish by submitting documentary evidence that you had entered into marriage in good faith but your marriage did not work out and that it was terminated due to divorce. You will become eligible for a waiver, if you establish that you were abused and subject to extreme cruelty by your spouse, though you and your spouse entered into marriage in good faith. In these cases , if your spouse is unwilling to file the petition to remove conditions jointly with you, you will be granted a waiver and permitted to file the petition by yourself.
Likewise, waivers will be granted to the conditional Green Card holders whose US citizen spouses have died and to the conditional residents who prove that their removal from the country would result in extreme hardship. Hence, as evidence, you will have to submit a variety of supporting documents along with Form I-751 and the evidence you need to provide will depend on your individual situation. In all these cases, you will have to submit documents to establish that you and your spouse entered into marriage in good faith, such as documents that contain your name and the name of your spouse, wedding photographs, birth certificates of your children, insurance statements, etc. USCIS after reviewing your request, will extend your status. You will be required to appear for an interview and if you are found to be eligible, you will be granted permanent resident status.