A USCIS case status can be tracked online by entering the receipt number assigned to your case. The Case Status Search can be found on the USCIS website under the "Tools" tab.
After submitting an application to USCIS, you receive a receipt notice in the mail. The notice explains further processing steps, and it provides a receipt number that can be used to track your case. Tracking your case on the USCIS website provides the most updated information regarding your application to USCIS, since the case tracker is often updated prior to any notice received by mail. The Case Status Search page also provides a number for USCIS customer service. If your receipt number has not been mailed to you by a specified date on the Case Status Search page, USCIS advises applicants to call this customer service number.
The Case Status Search page also provides an estimated time by which you should receive updated information regarding your case by mail. If you have not received your case information by mail, you are also advised to call the number listed on the Case Status Search page. The USCIS communicates with applicants primarily by mail, but tracking a case status ensures that an applicant receives the most updated information regarding his case.