Prior to its digitization in 2013, the departure portion of a paper I-94 form must be retained by the passenger at all times during their stay (passport control officers would usually staple this portion to the passport).
並在2013年对其数位化，I-94表格的出境部分必须由乘客在旅途中全程保留时间逗留期间(护照管控官员通常会把这部分钉在护照上)。