First day of issue, Washington DC 21 April 1982 shows a Library of Congress 20 cent stamp, the Library of Congress building in Washington DC, and the James Madison Memorial Annex.In 1957, Librarian of Congress L. Quincy Mumford initiated studies for a third Library building. Congress appropriated planning funds for that structure, today's James Madison Memorial Building, in 1960, and construction was approved by an act of Congress on October 19, 1965 that authorized an appropriation of $75 million. Excavation and foundation work began in June 1971, and work on the superstructure was completed in 1976. The cornerstone, inscribed with the date 1974, was laid on March 8, 1974. Dedication ceremonies were held on April 24, 1980, and the building actually opened on May 28, 1980. [SOURCE]

This is an August 4th 2005 first day of issue with a Presidential Libraries stamp honoring the Presidential Library of Lyndon B. Johnson. WASHINGTON – The U.S. Postal Service honored our Presidential Libraries with a commemorative postage stamp to coincide with the 50th anniversary of the Presidential Libraries Act of 1955. “The U.S. Postal Service is proud to conduct these First-Day-of-Issue dedication ceremonies at all of the nation's Presidential Libraries and Museums. These are truly national treasures,” said Postmaster General John E. Potter. “The new stamp will help honor the libraries' unique role in preserving and extending access to Presidential materials while recounting the lives and times of many of our nation's Presidents.” [SOURCE]