Before INS became part of Homeland (in)security, my future wife was denied admission to the U.S. because she had the intent to become a resident, but did not yet have a resident visa. Before my future wife could get a resident visa, we needed to get married; so we decided that Toronto, Ontario was the easiest place to go; so I booked her a flight BRU-ORD-YYZ. When she arrived at ORD, she was escorted from the Int. terminal 5 to the domestic-side terminal. She said that she was not allowed out of her escort's site until she boarded.

Note: In 2001, you could transit U.S. without a visa, even if you were inadmissable to the U.S.