The new address format affects all USCIS headquarters offices, the Arlington Asylum Office, and the Washington District Office. In order to ensure the timely delivery of USCIS correspondence addressed to the affected offices, USCIS has prepared a comprehensive list of unique mailstops and corresponding zip codes plus 4 numbers. The mail will be delivered to each office according to the mailstop and zip code plus 4 numbers provided. If the address does not list a mailstop and corresponding zip code plus 4 numbers, the correspondence will still be delivered but may be subject to minor delays as a result of the new mail process.