The Evangelical Lutheran Church in America (ELCA) is a mainline Protestant Lutheran church headquartered in Chicago, Illinois. The ELCA was officially formed on January 1, 1988, by the merging of three Lutheran church bodies. , it has approximately 3.04 million baptized members in 8,724 congregations. In 2015, Pew Research estimated that 1.4 percent of the U.S. population self-identifies with the ELCA. It is the seventh-largest Christian denomination by reported membership, and the largest Lutheran denomination in the United States. The next two largest Lutheran denominations are the Lutheran Church–Missouri Synod (LCMS) (with over 1.8 million baptized members) and the Wisconsin Evangelical Lutheran Synod (WELS) (with approximately 340,000 members). There are also many smaller Lutheran church bodies in the United States, some of which were formed by dissidents to the major 1988 merger. The ELCA belongs to the World Council of Churches, the National Council of Churches of Christ in the USA, and the Lutheran World Federation. The ELCA is in full communion with the Episcopal Church, Moravian Church, Presbyterian Church (USA), Reformed Church in America, United Church of Christ, and the United Methodist Church. Historically, various Lutheran church bodies in the United States had been formed resulting from immigration waves from various countries. For instance, members of the Lutheran Church in America (LCA) (centered in New York City, New York, and Philadelphia, Pennsylvania) were largely descendants of immigrants in the colonial and mid-19th century period. The American Lutheran Church (ALC), with headquarters in Minneapolis, Minnesota, was influenced by descendants of the waves of Scandinavian and German immigration to the Midwest in the late 19th and early 20th centuries. The Association of Evangelical Lutheran Churches (AELC) (which had earlier withdrawn from the LCMS after 1975), was made up of many congregations throughout the lower Midwest.