He was one of the first Presidents to build a Presidential Library
As a reader and lover of history throughout his long life, Harry Truman was acutely aware of the value of his papers to posterity. He believed that consolidating all of the records of his life in a single setting would provide a valuable tool to future historians, giving them insights into the events of a lifetime as measured against the trials and activities of both the President and the many who advised and counseled him.
His papers to be preserved included personal letters and diaries, notes, books read with the corresponding marginal notations of the reader, personal preferences, official documents and records, and all of the minutiae of his existence.
To create this archive, Truman actively participated in the raising of funds and the selection of a suitable site for his Presidential Library. One of the first steps was the writing and publication of his memoirs. When Truman left the presidency there was no financial provision for a pension, a staff, Secret Service protection for the ex-president or his family, or even the means to get home. President Eisenhower graciously lent the former President the private railcar Ferdinand Magellan to convey the President home. Truman did not drive home, despite a longstanding myth that he did.
To build his library, Truman solicited donations, made paid public appearances, wrote articles and op-eds for newspapers and magazines, and did whatever else he could to generate sufficient capital. His success and the ongoing dedication of others built the Truman Library, located in Independence Missouri.
The first to be built under the 1955 Presidential Libraries Act, which encouraged but did not fund such endeavors, it is now operated by the National Archives and Records Administration. Truman spent the last years of his life actively working at the library, training staff, giving lectures, and meeting with visiting students of all ages.