These documents cover the years 1874-1918, with most of the items dating from 1877-1878. They relate primarily to the early telephone industry, Edison's invention of the carbon telephone transmitter, and his relationship with the Bell Telephone Co. Also included are documents dealing with the Edison Speaking Phonograph Co., which was organized by several executives associated with the Bell Telephone Co., including Gardiner G. Hubbard, father-in-law of Alexander Graham Bell. Some of the items pertain to Edison's electric pen and duplicating press business, which was managed by George H. Bliss. There are occasional references to other topics, such as telegraphy and electric lighting.

The documents are arranged in the following order: (1) Emile Berliner Correspondence; (2) Francis Blake Correspondence; (3) George H. Bliss Correspondence; (4) Thomas E. Cornish Collection; (5) Thomas B. A. David Correspondence; (6) Thomas A. Edison Files; (7) Edison Speaking Phonograph Co. Records; (8) General Manager's Letterbooks; (9) Gardiner G. Hubbard Correspondence; (10) James J. Storrow Collection; (11) Thomas A. Watson Correspondence; (12) Western Electric Manufacturing Co. Records; (13) Western Union Records.