The Diocese of Allegheny is a former US Roman Catholic diocese (1876-1889) and present Latin episcopal titular see. In Latin, the see is known as Dioecesis Alleghenensis, the Diocese of Allegheny.
Roman Catholic Diocese of Allegheny Wikipedia
The diocese was created on 11 January 1876 on territory split from the Diocese of Pittsburgh, as a fellow suffragan of the Metropolitan Archdiocese of Philadelphia. The new diocese covered eight counties, with an area of 6530 sq. miles, leaving the parent diocese six counties and an area of 4784 sq. miles.
Bishop Michael Domenec (born on 1816.12.27 in Spain, ordained priest 1839.06.30, consecrated bishop on 1860.12.09) was appointed as its first and only proper ordinary.
When bishop Domenec died on 1877.07.29, Bishop John Tuigg of Pittsburgh was appointed Apostolic Administrator (1877 – 1889.07.01).
On 1 July 1889, the see was suppressed as a residential diocese and its territory was reunited with the diocese of Pittsburgh.
Since it no longer is a diocese for a diocesan bishop, it is today listed by the Catholic Church as a titular see.
The titular bishops of Allegheny have been:George Leo Leech (1971–1985)
Edward Egan (1985–1988), later a Cardinal
Patrick Joseph McGrath (1988–1998)
Robert Joseph McManus (1998–2004)
John Walter Flesey (2004 –), Auxiliary Bishop of Newark (USA)