The Vatican in 1804 asked Bishop John Carroll from the Diocese of Baltimore in the United States to send priests to the Virgin Islands.

In 1917, during World War I, the Government of Denmark sold the islands of St. Croix, St. John and St. Thomas to the United States.

In 1977, Paul VI elevated the prefecture to the Diocese of Saint Thomas in the Virgin Islands, naming Harper as its first bishop.

[4] Pope John Paul II in 1984 appointed Seán Patrick O'Malley from Washington as coadjutor bishop in St. Thomas to assist Harper.

Edward John Harper (1960–1977) Adalberto Martínez Flores (priest here, 1985–1993), appointed Auxiliary Bishop of Asunción, Paraguay in 1997