What is an Alien Registration Number?

Disclaimer: This is not individual legal guidance. You must consult with your own attorney as results may vary for every case.
Alien Registration Number, also referred as “A-number,” “A#,” or “USCIS number”, is a 7-9 digit identification number that USCIS assigns to non-citizens.
This helps the U.S. Government to better identify the millions of immigrants in the United States.
Short-term visitors suchs as students and tourists normally don’t get an Alien Registration Number.
On most forms that you’ll receive from USCIS, your Alien Registration Number will be labeled “A#” and posted prominently near the top of the first page.
Bear in mind that your A# is not the same as the Social Security Number (SSN), Visa Number, I-94 Number, USCIS Case Number, or USCIS Online Account Number.