The United Church of Christ came into being in 1957 with the union of two Protestant denominations: the Evangelical and Reformed Church and the Congregational Christian Churches. Each of these was, in turn, the result of a union of two earlier traditions.
The Congregational Churches were organized when the Pilgrims of Plymouth Plantation (1620) and the Puritans of the Massachusetts Bay Colony (1629) acknowledged their essential unity in the Cambridge Platform of 1648.
The Reformed Church in the United States traced its beginnings to congregations of German settlers in Pennsylvania founded from 1725 on. Later, its ranks were swelled by Reformed immigrants from Switzerland, Hungary and other countries.