Why would I be denied entry to the US?
Why would I be denied entry to the US? The most common reason a person may be refused entry to the US is improper documentation. Not having the correct visa for the purpose of the visit or no visa at all. if an applicant for admission arrived by air and is refused they will be put on a flight to return them to their point of embarkation.
How do customs know who to stop?
In the air passenger environment, air carriers transmit passenger information to CBP through the Advance Passenger Information System (APIS). CBP officers also rely on the Interagency Border Inspection System (IBIS) to determine which individuals to target for secondary examination upon arrival in the United States.