On June 5, 1837, the Presbyterian Church in the U.S.A. separated into Old School and New School divisions.
The split involved a series of issues related to theology, polity, and social reform (especially debate on the Presbyterian response to slavery). The Old School consisted of doctrinal conservatives mainly in the Mid-Atlantic states and the South; the New Schoolers were progressives concentrated in New York, New England, and the western frontier. The 1837 General Assembly, meeting with an Old School majority, abrogated its 1801 Plan of Union with the Congregationalists, it pronounced that action retroactive, and it thereby declared that four New School Presbyterian synods brought in by that plan to be out of the ecclesiastical connection of the Presbyterian Church of the United States of America.
This Assembly action launched a 32-year division between Old School and New School Presbyterians. In 1869, the two parties were united in the North, soon after the end of the Civil War. In the words of Princeton historian Lefferts Loetscher, the reunion of 1869 resulted in a broadening church, where organizational efficiency eclipsed theological precision. By the close of the nineteenth century, northern Presbyterians would experience both significant growth and advancing secularization.
- John Muether