Green Cards (also known as Permanent Resident Cards) do not always include the holder’s signature. In limited cases, the USCIS may waive the signature requirement for certain people, such as children under the age of consent or individuals who are physically unable to provide a signature.
Since February 2015, the USCIS been waiving the signature requirement for people entering the United States for the first time as lawful permanent residents after obtaining an immigrant visa abroad from a U.S. Embassy or consulate.
When the USCIS issues a Green Card without a signature, the card will say “Signature Waived” on the front and back of the card where a signature would normally be located. Green Cards are official documents issued by USCIS that identify the holder as a lawful permanent resident of the United States. The cards are also proof of identity and work authorization.
To learn more, please visit: http://www.uscis.gov/news/
(Adapted from information provided by the United States Citizenship and Immigration Services)