Background
O'Hara was born in Dungiven, County Londonderry, he came with his parents to the United States in 1820, settling at Philadelphia, Pennsylvania.
O'Hara was born in Dungiven, County Londonderry, he came with his parents to the United States in 1820, settling at Philadelphia, Pennsylvania.
After attending Georgetown College in 1832, he was sent by Francis Kenrick to study at the College of the Propaganda in Rome. He there earned his Doctor of Divinity degree with the highest honors. While in Rome, he was ordained to the priesthood by Cardinal Giacomo Filippo Fransoni on December 21, 1842.
He was the first of Scranton, Pennsylvania (1868–1899). O'Hara, following his return to Pennsylvania, was named an curate at St. Patrick's Church in Philadelphia. He then served as rector and professor of moral theology at St. Charles Borromeo Seminary.
He became pastor of St. Patrick's Church in 1856, and vicar general of the Diocese of Philadelphia in 1860. On March 3, 1868, O'Hara was appointed the first of the newly erected Diocese of Scranton by Pope Pius IX. He received his episcopal consecration on the following July 12 from James Frederick Wood, with s William Henry Elder and Patrick N. Lynch serving as co-consecrators, at the Cathedral of Sts. Peter and Paul. At the time of O'Hara's arrival in Scranton the following September, there were only 24 priests and parishes.
By the time of his death 30 years later, there were 152 priests, 100 parishes, and 32 parochial schools. He also founded St. Thomas College (later University of Scranton), an orphanage, and a hospital. O'Hara died after a long illness in Scranton, aged 82.
He is buried under the main altar of St. Peter's Cathedral.