The Presbyterian Church in the United States of America (PCUSA) was a Presbyterian denomination existing from 1789 to 1958. In that year, the PCUSA merged with the United Presbyterian Church of North America. The new church was named the United Presbyterian Church in the United States of America. It was a predecessor to the contemporary Presbyterian Church (USA).
The denomination originated in colonial times when members of the Church of Scotland and Presbyterians from Ireland first immigrated to America. After the American Revolution, the PCUSA was organized in Philadelphia to provide national leadership for Presbyterians in the new nation. In 1861, Presbyterians in the Southern United States split from the denomination because of disputes over slavery, politics, and theology precipitated by the American Civil War. They established the Presbyterian Church in the United States, often called the "Southern Presbyterian Church". The PCUSA, in turn, was described as the Northern Presbyterian Church. Despite the PCUSA's designation as a "Northern church", it was once again a national denomination in its later years.
Over time, traditional Calvinism played less of a role in shaping the church's doctrines and practices—it was influenced by Arminianism and revivalism early in the 19th century, liberal theology late in the 19th century, and neo-orthodoxy by the mid-20th century. The theological tensions within the denomination were played out in the Fundamentalist–Modernist Controversy of the 1920s and 1930s, a conflict that led to the development of Christian fundamentalism and has historical importance to modern American evangelicalism. Conservatives dissatisfied with liberal trends left to form the Orthodox Presbyterian Church in 1936.