Previously all first-time immigrant travelers to the United States were required to hand-carry an Immigrant Visa (IV) packet and present it at the U.S. Port of Entry to the Customs and Border Protection authorities. In 2017, the Department of State began to use an online application center to collect, review, and process the required documents previously contained in the IV packet.
Immigrant Visa (IV) packets are now transmitted electronically to Customs and Border Protection and are accessible at the U.S. Port of Entry.
Any immigrant traveler carrying a visa with a special annotation is not required to hand-carry an IV packet.
You can find additional information on electronic processing here.