After secessions due to the slavery issue and the movement of New School Presbyterian-affiliated missionaries to the Presbyterian Board of Foreign Missions, the ABCFM was left as a Congregationalist body after 1870. The American Board, as it was known continued to operate as a largely Congregationalist entity until the 1950s. In 1957, the Congregational Christian church merged with the German Evangelical and Reformed Church to form the United Church of Christ. As a part of the organizational merger associated with this new denomination, the ABCFM ceased independent existence and merged operations with other missions entities to form the United Church Board for World Ministries, an agency of the United Church of Christ.