- Manuscript draft of a four-page letter dated January 19, 1846, from Lysander Spooner in Athol [Massachusetts] to George Bradburn in Boston [Massachusetts], asking Bradburn to solicit prominent names to sign a petition and then have the petition presented to the United States legislature., New-York Historical Society
- Two-page letter from Bela Marsh in Boston, Massachusetts to Gerrit Smith, dated September 29, 1849, regarding a resolution to distribute Lysander Spooner's work, the Unconstitutionality of Slavery to lawyers. At end, manuscript copy of Smith's response, dated October 7, 1849, in Smith's hand., New-York Historical Society
- One-page letter and envelope from Bela Marsh in Boston [Massachusetts] to Lysander Spooner in Worcester [Massachusetts], dated October 11, 1849, in which he forwards a transcription of Gerrit Smith's reply to Marsh's inquiry about distributing Spooner's book to United States lawyers., New-York Historical Society
- One-page letter dated January 5, 1855, from William Goodell on behalf of the American Abolition Society in New York, to Lysander Spooner in Boston, Massachusetts, ordering a supply of his book, The Unconstitutionality of Slavery, for distribution to all members of Congress, as well as additional copies to sell and give away., New-York Historical Society
- Two-page letter from Gerrit Smith in Peterboro [New York] to Lysander Spooner in Boston, Massachusetts, dated November 6, 1855, in which he expresses his pleasure that Spooner is writing an argument "on the Wilhelm case" and discusses the distribution of 300 copies of Spooner's book, "the Unconstitutionality of Slavery.", New-York Historical Society
- Manuscript copy of a four-page letter from Gerrit Smith of Peterboro [New York] to Hon. D. [David] Wilmot, dated March 20, 1856, in which he responds to a letter from Wilmot discussing slavery and the United States Constitution, and sends him a copy of Lysander Spooner's "the Unconstitutionality of Slavery.", New-York Historical Society
- Undated pledge of moneys to be paid to Lysander Spooner for "a review of Judge Kane's late decision, that the U.S. Courts have no constitutional right to punish for contempt without trial by jury." Signed by several prominent abolitionists, including Ellis Gray Loring, Francis Jackson, and Samuel E. Sewall., New-York Historical Society