A-number
U.S. Naturalization Test (2025 Standard) glossary · English
Definition
Your Alien Registration Number (the "USCIS #" on your green card); you keep it in your records but stop using it once you naturalize.
A-number in plain English
Your A-number (the 'A' stands for 'Alien,' the government's word for a non-citizen) is like a personal ID number USCIS uses to keep track of your immigration file. You'll find it printed on your green card, and it links to all your paperwork. Once you become a citizen, this number is retired because you're no longer a non-citizen in their system, so they don't need it anymore.
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