The Presbyterian Church (USA), or PC(USA), is a mainline Protestant Christian denomination in the United States. Part of the Reformed tradition, it is the largest Presbyterian denomination in the U.S., and known for its relatively progressive stance on doctrine. The PC(USA) was established by the 1983 merger of the Presbyterian Church in the United States, whose churches were located in the Southern and border states, with the United Presbyterian Church in the United States of America, whose congregations could be found in every state.