- Series 1 General Correspondence. 1651-1827.
- Series 2 Horatio Gates Letterbook Correspondence. 1780-81.
- Series 3 District of Columbia Miscellany. 1790-1808.
- Series 4 Account Books.
- Series 5 Commonplace Books.
- Series 6 Randolph Family Manuscripts. 1790-1889.
- Series 7 Miscellaneous Bound Volumes.
- Series 8 Virginia Records Manuscripts. 1606-1737.
- Series 9 Collected Manuscripts. 1783-1822.
- Series 10 Addenda to the Thomas Jefferson Papers. 1781-1829.
The Thomas Jefferson Papers at the Library of Congress is organized into ten series.
Series are the groupings by which archivists organize or maintain manuscript collections. Series can be based on a number of organizational principles. One principle is that of their original creation, when that is still evident or can be accurately determined. Series 6 of the Thomas Jefferson Papers, the Randolph Family Manuscripts, and Series 8, the Virginia Records, were original manuscripts acquired by Jefferson during his lifetime. Most of their original organization remains.
Series 2, the Horatio Gates Letterbook Correspondence, was created by Jefferson himself. Jefferson maintained letterbooks as governor of Virginia in 1780-81. These were lost, however, when Benedict Arnold raided Richmond during the American Revolution. To replace this lost correspondence, Jefferson borrowed the letterbook of Revolutionary War general, Horatio Gates, in 1793 and had a copy of it made for his own reference.
Jefferson's correspondence is found mainly in Series 1, which occupies approximately three-fourths of his Papers and has been organized chronologically by an archivist. It is not unusual in an eighteenth-century collection for correspondence to occur in two different kinds of series: a letterbooks series containing copies of outgoing letters, and a general correspondence series containing original incoming letters. This is the case in the George Washington Papers at the Library of Congress. In contrast, Jefferson's incoming and outgoing correspondence can both be found together in Series 1. Instead of letterbooks, Jefferson made letterpress copies of his outgoing correspondence. These letterpress copies reproduced the manuscript leaves of the original and could then be interfiled with incoming correspondence. Letterpress copies were made by laying damp tissue against the ink side of a manuscript leaf and then pressing the damp tissue face down on a new leaf. Letterpress copies have a very distinctive appearance. The pen strokes appear thicker: Thomas Jefferson to Maria Hadfield Cosway, October 12, 1786.
Jefferson also made polygraph copies of his correspondence. The polygraph was a copying machine utilizing two or more pens on springs so that what was written on one sheet of paper was duplicated on others. Jefferson worked with Charles Willson Peale to develop the machine. Peale held the rights to the invention. It is extremely difficult to distinguish a polygraph copy of a letter from the one written with the hand-held pen. With both the original and the polygraph copy in hand, one might, with a spectrograph, be able to measure the depth of ink. Presumably, the one written with a hand-held pen would have a greater depth of ink. Jefferson probably varied in which one he sent to a recipient. There are most likely some polygraph copies of letters in Series.
Series can also be organized by subject matter. Series 3, District of Columbia Miscellany, was once part of a subject-area collection on the building of the federal city. It was created by the State Department from various presidential papers it held in the nineteenth century. In 1922, after all the presidential papers had been transferred from the State Department to the Library of Congress, this artificial collection was broken up and its parts returned to their respective presidential collections. In the Thomas Jefferson Papers, this returned material was maintained as a separate subject series.
Another common basis for the organization of series is document type. Series 3, District of Columbia Miscellany, contains a variety of document types--letters, notes, drawings, and so forth--ranging over one subject area. In contrast, Series 4 and 5 are each based on one kind of document. Series 4 consists of account books and Series 5 of commonplace books. In the former, Jefferson maintained household and personal accounts. In the latter, he copied extracts from legal and literary sources for his own reference. Account books and commonplace books are both distinct kinds of documents that merit series of their own.
No collection of papers is complete without a series that is miscellaneous. In the Jefferson Papers, this is Series 7, Miscellaneous Bound Volumes, and also Series 9, Collected Manuscripts. Each of the nine volumes in Series 7 addresses a different subject. These volumes range from weather records to a list of books in Jefferson's library, from his 1801 Parliamentary Manual to his handmade volume of clippings taken from different language editions of the New Testament. Series 9, a small series, contains miscellaneous Jefferson manuscripts collected by the Library of Congress after 1920.
Series 10, Addenda to the Thomas Jefferson Papers, consists of a selection of letters and other materials acquired after the bulk of the collection had been processed and microfilmed. These manuscripts were scanned in their original format.