Although the two accessions were interfiled, whenever possible the papers were kept in their original order. The researcher should check all three sections for any particular correspondent or subject, because the dates of the files and the correspondents' names often overlap. After Bush retired as president of the Carnegie Institution in 1956 he returned to Belmont, Massachusetts, where he remained until his death in 1974. The bulk of this collection is from these retirement years. Bush remained actively involved in scientific and other organizations that ranged from the American Academy of Arts and Sciences and the Carnegie Institution to the Cape Cod Pilgrim Memorial Association and the Library of the Boston Athenaeum.
Personal correspondence is mixed with professional papers.
Reflected throughout the files are Bush's friendships with scientists and statesmen and his continuing interest in scientific matters. For example, correspondence with Philip Abelson, Ira Bowen, James Conant, and Merle Tuve reveals some of Bush's ideas on relativity. He also exchanged ideas with scientists and engineers about hydrofoil boats, medical instrumentation, and other subjects. When he returned to Massachusetts, Bush started to invent again. His files contain correspondence, working notes, data from experiments, and patent records about these inventions.