The U.S. State Department Central Files are the definitive source of American diplomatic reporting on political, military, social, and economic developments throughout the world in the 20th century. Concentrating exclusively on those Central Files that have not been microfilmed by the National Archives or other publishers, UPA's microfilm editions of the Central Files nonetheless dwarf the State Department's very selective volumes of the Foreign Relations of the United States (FRUS). Containing less than one percent of the material in the Central Files, FRUS focuses on U.S. relations with individual countries but does not include coverage of many of the key topics to which the majority of the original files are devoted. Each part of the Central Files contains a wide range of materials from U.S. diplomats in foreign countries: special reports on political and military affairs; studies and statistics on socioeconomic matters; interviews and minutes of meetings with foreign government officials; court proceedings and other legal documents; full texts of important letters, instructions, and cables sent and received by U.S. diplomatic personnel; voluminous reports and translations from foreign journals and newspapers; and countless translations of high-level foreign government documents. By 1959, the end of colonial rule approached all of sub-Saharan Africa. The Central Files document this historic political trend as it emerged. Sudan chose independence in 1956, after public opinion shifted against union with Egypt. Ghana was granted independence in 1957 following three consecutive electoral victories by the Conventional People's Party, the most hard-line nationalist party in Ghana. The western and eastern regions of Nigeria formally became self-governing in 1957, and a Federal Executive Council prepared for full independence, despite ethnic and regional tensions and legal restrictions on political activities.