It has an area of 119,439 sq. km. with a population of 650,000, of whom 82,847 are Catholics distributed in 61 parishes with 60 diocesan priests and 70 regular clergy. It has a major and a minor seminary; 17 male and 39 female religious communities (Ann. Pont. 1953, p. 442).
Christianity likely appeared with the establishment of Spanish Franciscans on the nearby island of Vancouver in the late 18th century, but nothing precise is known of their apostolate on the mainland. On 24 November 1838, two priests from Québec, N.-Fr. Blanchet and M. Demers, arrived at Fort Vancouver, then an important fur-trading post. They remained until October 1839, when they moved to Oregon. In the following years the region was intermittently evangelized by M. Demers, Fr. De Smet, SJ, in May 1842, and by Fr. Giovanni Nobili, also a Jesuit, who for a time served as a missionary in what was then called New Caledonia. On 13 September 1860 the Oblates of Mary Immaculate established themselves in the new town of New Westminster and became the sole missionaries throughout the present territory of the archdiocese. On 14 December 1863 the Apostolic Vicariate of British (Canadian) Columbia was erected and entrusted to Bp. L.-J. d’Herbomez. In the same city of Vancouver,
Pius IX, who on 6 March 1864 recalled the monks of the Abbey of Casamari, who still reside there.
The architecture of the church and monastery is of Cistercian type, Gothic-Lombard in style (after 1240). The interior has three naves; of great artistic effect is the circular rose window above the main entrance, which dominates the most elegant façade, much admired by historians of the Abbey. In the church are preserved fine works by Pomarano, Muziano and the Sermonetan Girolamo Siciolante (d. 1541). Elegant too is the architecture of the cloister, adorned with a double row of marble columns supporting the four lateral façades.