At the First Council of Nicaea (325) this position of the metropolitan was taken for granted, and was made the basis for conceding to him definite rights over the other bishops and dioceses of the state province. In Eastern canon law since the fourth century (cf. also the Synod of Antioch of 341, can. ix), it was a principle that every civil province was likewise a church province under the supreme direction of the metropolitan, i.e. of the bishop of the provincial capital.
This division into ecclesiastical provinces did not develop so early in the Western Empire. In North Africa the first metropolitan appears during the fourth century, the Bishop of Carthage being recognized as primate of the dioceses of Northern Africa; metropolitans of the separate provinces gradually appear, although the boundaries of these provinces did not coincide with the divisions of the empire. A similar development was witnessed in Spain, Gaul, and Italy. The migration of the nations, however, prevented an equally stable formation of ecclesiastical provinces in the Christian West as in the East. It was only after the fifth century that such gradually developed, mostly in accordance with the ancient divisions of the Roman Empire. In Italy alone, on account of the central ecclesiastical position of Rome, this development was slower. However, at the end of Antiquity the existence of church provinces as the basis of ecclesiastical administration was fairly universal in the West. In the Carlovingian period they were reorganized, and have retained their place ever since.
By contrast there have always been, and are today, individual dioceses which do not belong to any province, but are exempt, i.e. directly subject to the Holy See. In April 2006, there are 527 metropolitan sees, not counting a few who are given a more exclusive name because of the higher status of their Archbishop: 4 Major archdioceses and 9 Patriarchates, nor the Papacy (which in 2006 abandoned the title of Patriarch of the West for its see of Rome).
The authority of the Metropolitan over the suffragan sees is very limited (for example, during a vacancy, a Metropolitan can name a temporary Administrator if the College of Consultors of the diocese fails to elect one within a set time and the Pope has not named an apostolic administrator). Thus, the Metropolitan is not an ordinary with respect to the ecclesiastical province, only within his own archdiocese.
The borders of provinces have often been inspired, or even determined, by historical and/or present political borders; the same is often true of diocesan borders within a province. For example, in southern Germany the diocesan boundaries follow the political boundaries that existed between 1815 and 1870. In the United States, Roman Catholic ecclesiastical provinces typically follow state lines, with less populous states being typically grouped into provinces and more populous states being a province by themselves. With one exception, California and Texas are the only states with multiple provinces, with each state having two metropolitan archdioceses. Maryland is unusual in that its Eastern Shore shares a diocese with another state, that of the Diocese of Wilmington, and the Maryland suburbs of Washington share an Archdiocese of Washington with the District of Columbia. The Archdiocese of Washington constitutes the bulk of a province separate from that of the surrounding Province of Baltimore. Most countries are constituted a province or divided into several, except those with a small population and/or quite small numbers of Roman Catholics; thus when a nation that was part of another province achieves independence, it is likely within a few years to have at least one raised to Metropolitan rank.
The word "province" is also used to refer to groupings of dioceses within a member church. The Church of England is divided into two provinces: Canterbury and York. The Anglican Church of Australia has five provinces: New South Wales, Queensland, South Australia, Victoria and Western Australia, and an extraprovincial diocese. The Anglican Church of Canada has four: British Columbia and the Yukon, Canada, Ontario, and Rupert's Land. The Church of Ireland has two: Armagh and Dublin. The Church of Nigeria and the Episcopal Church in the United States of America both number, rather than name, their provinces. Nigeria has three and ECUSA has nine.
A province of a religious community is typically headed by a provincial superior. The title differs by each congregational tradition (provincial minister for Franciscans; provincial prior for Dominicans; simply "provincial" or "provincial father" for the Jesuits and many others, for instance). The borders of such juridsdictions are determined independently of the diocesan structure, and so often differ from the abovementioned 'secular' ecclesiastical provinces, usually far larger in most parts of the word, sometimes even smaller in a congregation's heartland, while many are absent from large parts of the world.
Most monastic orders do not use provincial distinctions. In general, they organize their administration through autonomous houses, in some cases grouped in larger families (e.g., each Benedictine abbey is an independent foundation, but they often choose to group themselves into "congregations" based on historical connections).