National Diet Library
In December 1947, Clapp left for Japan as head of the Library of Congress mission to Tokyo, Japan to coordinate legislation for and establishment of the Japanese National Diet Library. His work garnered praise from the Supreme Commander of the Allies Douglas MacArthur and Hitoshi Ashida, Japanese Foreign Minister and, later, Prime Minister. The National Diet Library (NDL) inherited collections from the Imperial Diet libraries (established 1890) and the Imperial Library (established 1872). Following the direction of the U.S. Library mission, Article 130 of the Diet Law of 1948 declared, "The National Diet Library shall be established in the Diet by a separate law, in order to assist Diet Members in their study and research."