USCIS assigns a receipt number for every green card application received. This is a 13-character ID, beginning with three letters that can be used to check the application status.
Steps to Check Status of Green Card Application
To check status online:
Log on to the USCIS website, enter the application receipt number, and click “Check Status”.
To check status by telephone:
Call USCIS National Customer Service Center at (800) 375-5283. When prompted, enter the application receipt number.