You can enter the US through over 300 Ports-?of-?Entry (POE). A POE is any station: land, air or water, through which a person can enter the US. Immigration officials inspect all persons entering the US at a port?of?entry. At the port of entry, an official must authorize the visitor's admission to the U.S. At that time Form I?94, Record of Arrival/?Departure, which notes the length of stay permitted, is stamped. Those visitors who wish to stay beyond the time indicated on Form I?94 must contact the USCIS to request Form I?539, Application to Extend Status. The decision to grant or deny a request for extension of stay is made solely by the USCIS.