Ellis Island

Ellis Island was a federal enclave in New York City and Jersey City, that served as the United States' busiest immigrant inspection station from 1892 until 1954. It was a gateway for an estimated twelve million immigrants entering the country. It was located half of a mile from the Statue of Liberty's Liberty [formerly Bedloe's] Island.

In 1892, Jack Harkness got into a fight at the immigration centre, whereupon a man shot him though the heart. This caused his second death and proved to him he could not die. (TV: Utopia)

Jack passed through Ellis Island again in 1927, where he met Angelo Colasanto. (TV: Immortal Sins)

In 1966, the disused Ellis Island and other New York City landmarks were observed by the First Doctor, Ian Chesterton, Barbara Wright, and Vicki Pallister, whilst the TARDIS was preparing to materialise atop the Empire State Building. (TV: The Chase)

Behind the scenes
Neither United States nationals nor tourists with return passage were processed at Ellis Island; the island was strictly an immigration centre. Speaking fluent English in an American accent, Jack Harkness would have been assumed to be an American without a second thought, even without a passport. The United States had no passport requirements for its nationals until late 1941, exclusive of certain wartime periods.