The papers of Jeremiah Sullivan Black (1810-1883) span the years 1813-1904, with the bulk of the items concentrated in the period 1856-1880. The collection includes correspondence, legal papers, articles, scrapbooks, and other papers relating to such subjects as the turmoil over slavery in Kansas before the Civil War, John Brown's raid on Harpers Ferry, Virginia, the impeachment of President Andrew Johnson, the Crédit Mobilier, the trial of Jefferson Davis, Black's efforts on behalf of Clement Claiborne Clay, and Jacob Thompson's letters from his exile in Europe following the Civil War. A large part of the material relates to various legal matters in which Black was involved.

The General Correspondence comprises the bulk of the collection and includes an important group of James Buchanan's letters relating to the closing days of his administration. Among these is Buchanan's draft of the defense of his actions with regard to Forts Sumter and Moultrie. There is also a group of letters written by Edwin M. Stanton during the years 1857-1858. Correspondence of Black's son, Chauncey, concerns Ward Hill Lamon's (1895), apparently written by Black and claimed by him to have been published with unauthorized changes. There is a large number of letters from Speaker of the House of Representatives, Samuel J. Randall, to Chauncey Black on important phases of Pennsylvania politics. Prominent among Jeremiah S. Black's correspondents are Thomas Francis Bayard, Montgomery Blair, Caleb Cushing, John C. Frémont, James Abram Garfield, Joseph Holt, and Reverdy Johnson. Among the correspondents of Chauncey Black are Charles A. Dana, William H. Herndon, Ward H. Lamon, James R. Osgood and Company, Samuel J. Randall, Don Piatt, J. M. Cooper, Wayne MacVeagh, and Daniel Sickles.. A partial card index of correspondents is available in the Manuscript Reading Room.

Included in the Writings series is Jeremiah S. Black's notes containing information on the last four months of Buchanan's administration, an account of his own resignation, and the cabinet meeting on Major Richard Anderson's removal to Fort Sumter. Chauncey Black's unpublished draft of the last chapter of Ward Hill Lamon's book on Lincoln is also filed in this series.

An addition to the collection contains family correspondence consisting primarily of letters from Black to his wife, Mary, and to his children. Other family members represented in the addition include Henry Clayton and Jeremiah S. Black Clayton.