The modern Ruthenian Greek Catholic Church originated at the Union of Uzhhorod in 1646, when Orthodox East Slavs with a Rusyn identity in the Carpathian Mountains entered into communion with the Pope.

[3] Ruthenia was originally the Latin term for the Rus' people, from which the name Russia was also derived, but later on, especially after the Schism of 1054 led to the separation of the East Slavs from Rome with Eastern Orthodoxy, its definition was narrowed.

In 1646, further to the south in Hungary, the Slavs in the Eastern Carpathians with a Rusyn identity who entered communion with Rome at the Union of Uzhhorod were also called Ruthenians.

The present structure of the Ruthenian Greek Catholic Church traces its origins to the 1646 Union of Uzhhorod, when Eastern Orthodox clergy were received into communion with the Holy See of Rome.

The resulting dioceses retained their Byzantine patrimony and liturgical traditions, and their bishops were elected by a council composed of Basilian monks and eparchial clergy.

In this part of central and eastern Europe, the Carpathian Mountains straddle the borders of the present-day states of Hungary, Poland, Slovakia, Romania and Ukraine.

At their persistent request, the Sacred Congregation for the Propagation of the Faith applied, on 1 May 1897, to the United States[12] rules already set out in a letter of 2 May 1890, to François-Marie-Benjamin Richard, the Latin Archbishop of Paris.

Ethnic tensions flared due to cultural differences (mostly of a political nature) between Ukrainians who came from Austrian-ruled Galicia and the Rusyns and other Byzantine Catholics who came from the Kingdom of Hungary.

This caused Rome to split the groups after Ortynsky's death, creating two ecclesiastical administrations for Eastern-rite Catholics in the United States, divided along nationality lines: one Ukrainian and the other Carpatho-Rusyn.

Clerical celibacy of American Eastern Catholics was restated with special reference to the Byzantine/Ruthenian Church by 1 March 1929, decree Cum data fuerit, which was renewed for a further 10 years in 1939.

[18] As of 2016[update], the membership of the Ruthenian Greek Catholic Church was estimated at some 419,500 faithful, with seven bishops, 664 parishes, 557 priests, 76 deacons, and 192 men and women religious.