The Greek Catholic Union of the USA (GCU) is the oldest continuous fraternal benefit society for Rusyn immigrants and their descendants in the United States, and established a Byzantine Catholic Church, Saint Nicholas Chapel, near their home office in Beaver, Pennsylvania.
The society was formed by the union of fourteen independent Greek Catholic lodges.
Many local units, or "Subordinate Lodges", grew out of the Churches parishes and a spiritual advisor is one of the regular officers.
GCU was active politically in the early twentieth century, especially in securing a place for Rusyns in the new nation of Czechoslovakia.
Also GCU consistently opposed the notion that Rusyns are Ukrainians, arguing instead that they are a distinct nationality.