How long does it take to get the green card after marrying a US citizen?

If you were admitted (given a white I-94 card or stamped in your passport) and have not left since that entrance, you are initially eligible to adjust status. If you are otherwise eligible, your marriage is bona fide and you are not inadmissible, the preparation of the filing takes about three weeks and then it generally takes CIS about 4-6 months to complete the processing. You'll have your fingerprints taken for security check and you and your spouse will have an interview with the local CIS folks for them to determine the bona fide nature of your marriage. I always encourage people in this situation to retain experienced counsel and let them handle the matter.

If you file the correct documents with supporting evidence as requested in the Instructions, the local USCIS office states : Field Office Processing Dates for Dallas TX as of: September 30, 2011 Form Form Name Processing Timeframe: I-485 Application to Register Permanent Residence or to Adjust Status 4 Months

In most cities, about 4-6 months. Please see