As of 2015, international visitors entering or departing the United States by land are required to complete an I-94 Arrivals/Departure Record, which requires the traveler’s name, birth date, passport number, country of passport issuance and date of entry, among other things, according to U.S. Citizenship and Immigration Services. A valid I-94 proves the visitor is in the United States legally.
When entering or leaving the United States by air or sea, foreign visitors to the United States are not required to complete an I-94 form, according to U.S. Customs and Border Protection. This information is automatically compiled by Customs and Border Protection from electronic travel records.
To prove that a foreign visitor who arrived by air or sea is in the United States legally, in lieu of the paper I-94 form, the foreign visitor can go to the Get I-94 Information Web page on the U.S. Customs and Border Protection website, agree to the conditions, and click Submit. Next, the visitor enters his last name, first name, birth date, passport number and country of issuance. He can then click the appropriate button for the needed information, either Get Most Recent I-94 or Get Travel History.
For international visitors entering the United States by land, the paper I-94 that has been stamped and verified by Customs and Border Protection is proof the visitor is in the United States legally. When the visitor leaves the United States by land, he must turn in his I-94 to a Customs and Border Patrol Officer.