"By 1814 when the British burned the nation's Capitol and the Library of Congress, Jefferson had acquired the largest personal collection of books in the United States. Jefferson offered to sell his library to Congress as a replacement for the collection destroyed by the British during the War of 1812. Congress purchased Jefferson's library for $23,950 in 1815. A second fire on Christmas Eve of 1851, destroyed nearly two thirds of the 6,487 volumes Congress had purchased from Jefferson."
"By 1814 when the British burned the nation's Capitol and the Library of Congress, Jefferson had acquired the largest personal collection of books in the United States. Jefferson offered to sell his library to Congress as a replacement for the collection destroyed by the British during the War of 1812. Congress purchased Jefferson's library for $23,950 in 1815. A second fire on Christmas Eve of 1851, destroyed nearly two thirds of the 6,487 volumes Congress had purchased from Jefferson."
https://www.loc.gov/exhibits/jefferson/jefflib.html