When Constantine the Great first organized the Church into Dioceses and Provinces, he used the existing Roman Empire’s existing administrative structure. Thus, Bishops, who already supervised (the Greek word that is translated “bishop” is “episcopos”, which literally means “overseer”) one or more Churches now became responsible for all the Christians in a given geographic area—the Roman “diocese”. All the dioceses in a given province were placed under the governance of a single Bishop, who became known as an “Archbishop”, or “high” bishop. Since this “arch” bishop was to supervise all the Bishops in a given geographic province (think “Gaul”, or “Judea”), he was generally expected to live in the capital city of that province. As a result, an alternate name for his office became “metropolitan” because the capital city was normally the largest city in the province. The name “metropolitan” is rarely used in this country, or most of the western Church, for that matter, but it is still in use. There are, according to The Catholic Encyclopedia, thirty-three “provinces” in the United States, made up of 148 Dioceses. Each Province has an Archbishop, or “Metropolitan”, and each Diocese a Bishop. In addition, there are several special case Bishops: The Military Archdiocese; four Eastern-Rite jurisdictions immediately subject to the Holy See in Rome. The Eparchies of St. Maron (Maronites), Newton (Melkites), St. Thomas the Apostle of Detroit (Chaldeans) and St. George Martyr of Canton, Ohio (Romanians). The Maronites, Melkites, Chaldeans and so forth are Eastern Christians that we’ve spoken of, before, who were generally independent of any Patriarchal oversight until the last Century, when the Roman Catholic Church pushed a world-wide mission to bring all such “other” Churches under Roman supervision. Today there are twenty-something such “Ordinariates” around the world. “Ordinary” is an alternate name for an “ordinary” Bishop: one who supervises one Diocese.
Other Churches follow generally the same geographic divisions, still, today. The Anglican Communion, for instance, has branches in Canada, Australia, the United States, South America, Africa, India and elsewhere. Fundamental to the formation of the Anglican Church in the 1500s was national independence, so the head of the Church in each nation (which is generally called a Province, even though it’s not) is an Archbishop. In some Churches he’s called the “Presiding Bishop”, but it means the same thing. The Greek Orthodox Church is much the same, as are the Russian Orthodox and other Eastern Churches. Interestingly, many of them are today headquartered here in the United States rather than in the countries where they started. It’s called “Freedom of Religion”. We have it. Most places don’t.