The John Parker Hale correspondence is made up of 16 letters received by Hale, a New Hampshire lawyer and antislavery politician, between 1833 and 1856. The earliest 6 letters (1833-1840) concern his career as an attorney in Dover, New Hampshire, and his personal life; the final 10 letters (1844-1856) relate to Hale's outspoken opposition to slavery while serving in the United States Congress in the 1840s and 1850s. With the exception of Boston resident George W. F. Mellen, who wrote 4 letters between April and July 1848, each author contributed 1 letter.
Hale received 6 letters from different writers in Massachusetts and New Hampshire between March 19, 1833, and August 13, 1840, pertaining to legal issues and to aspects of the authors' everyday lives, including the deaths of family members and an attempt to gain a political appointment as "carrier of the electoral vote" (August 13, 1840). The remaining 10 letters (December 13, 1844, and March 8, 1856), often written in depth, relate to the authors' opinions on slavery and to the impact of that issue on contemporary United States politics, such as the role of states' rights in national governance, the potential effect of abolition on the country's existence, and the significance of having a slaveholding president and slaveholding members of Congress. Others mentioned the moral and religious aspects of slavery in addition to providing political arguments. Many commended Hale for his antislavery speeches. Most of the political letters are dated 1848. In a letter dated September 30, 1852, a little over a month before the Presidential election, George Buchanan, "an Artist… & a Liberty man" requested Free Soil nominee John P. Hale's daguerreotype likeness.