The Reformed Church in the United States (RCUS) was originally overseen by the Dutch Reformed Church. In 1747 the German congregations formed their own Coetus, separating completely from the Dutch churches when they held their own synod in 1793.
The Eureka Classis was formed in 1910 of churches in North and South Dakota. Seeing the union of the RCUS with the Evangelical Synod of North America (ESNA) as compromising their Calvinism, the Eureka Classis declined to participate in the 1934 merger to form the Evangelical and Reformed Church. In 1942 the classis incorporated as the continuing Reformed Church in the United States.
In 1957, the Evangelical and Reformed Church merged with the majority of the Congregational Christian Churches (CC) to form the United Church of Christ (UCC), a body noted for its strongly liberal doctrine and moral stances.
The RCUS holds to the same Forms of Unity - Heidelberg Catechism, Belgic Confession, and Canons of Dort - as most Dutch Reformed groups.
The RCUS has an online directory of its congregations in California, Colorado, Iowa, Maryland, Minnesota, Missouri, Nebraska, North Dakota, Ohio, Pennsylvania, South Dakota, Wisconsin, and Wyoming.