Definitions of I-94 card
A small green or white card given to all nonimmigrants when they enter the United States. The I- 94 card serves as evidence that a nonimmigrant has entered the country legally. It is stamped with a date indicating how long the nonimmigrant may stay for that particular trip. It is this date-- and not the expiration date of the visa-- that controls how long a nonimmigrant can remain in the United States. A new I- 94 card with a new date is issued each time the nonimmigrant legally enters the United States. Canadian visitors are not normally issued I- 94 cards.