"U" is for the United Presbyterian Church in the U.S.A. The denomination was formed in 1958 with the union of the Presbyterian Church in the United States of America and the United Presbyterian Church in North America. Long-established lowcountry black congregations were part of the United Presbyterian Church. In 1861 when the South seceded from the union, the denomination had divided into northern and southern branches. After the war, black Presbyterians withdrew from white churches. With the assistance of northern missionaries and money, they organized an extensive school system built around local congregations. By 1917 there were 47 Presbyterian schools in the state on Edisto Island and in Irmo, Aiken, Cheraw, and Chester. In 1983, the southern branch of the Presbyterian Church joined with the United Presbyterian Church to form the Presbyterian Church [USA].