Included with these letters are botanical remarks addressed to John Torrey (1835), and a list of plants wanted by Rafinesque (ca. 1837).

These manuscripts include a few letters to John Torrey, Amos Eaton, and Reuben Haines, and journals of travels to the Appalachian mountains (1833), and to the source of the Schuylkill River (1834).

These letters are principally to his brother John Cleaves Short, on personal, family, and general topics.

The largest portion of correspondence is with Charles Edwin Bessy on botanical matters, including botanical publications in the United States and Europe, and plants and shell specimens.

These papers include letters on natural history, metals and mineralogy, botany, insects, the geological survey of New York, and analyses of distilled liquors in the cause of temperance.

This is primarily a collection of letters, with some additional documents, concerning Young's interest in botany, geology, mineralogy, and natural history. There is information about Bowdoin College, where he studied under Parker Cleaveland. There is also much on the natural history of Maine, where he was the State Botanist in 1847-1849, and also on the Bangor Natural History Society. There are materials on Brazil in relation to Young's service there as the U.S. consul to Rio Grande do Sul from 1863 to 1873. There are also letters from his brother, John C. Young, and his sister, Sarah Augusta Young.