The 1811 letter is from Henry Neill (1783-1845) to his father John Neill (1749-1816) and concerns family matters. The majority of the 1840s letters are written among members of the Neill family. There are letters to Edward Neill when he was a student at Amherst and Andover colleges from his father Henry (1841-1845), his brother Tom, his sister Emily, his mother Martha, and his cousin C. B. Duffield. Tom's letters (November 1843-April 1847) give details on cadet life, examinations, courts martial, and celebrations while he was a student at West Point Military Academy. They mention the visit of a French General Bertrand (November 2, 1843) and of a McLellan [possibly George Brinton McClellan] (July 23, 1844). Letters from 1845 to 1847 relate to Neill and his fiancee Nancy Hall of Snow Hill, Maryland, and to Neill's father's death in 1845. Additional letters discuss family matters, Neill's schooling, his views on religion, and his indecision over his chosen ministerial career. Letters written to Nancy from June to September 1847 give some data on his missionary work in Illinois, and his views on religious toleration in Virginia and slavery (July 5, 1847). There is no correspondence for 1848 and only one letter for 1849, which describes to his wife his trip to Prairie du Chien and his decision to leave Galena, Illinois.

Letters from the 1850s reveal Neill's many trips to the East. He visited Philadelphia, Washington, D.C., Amherst College, Cleveland, and New York City. These letters contain many references to family and friends, Minnesotans he met in Washington, and descriptions of places he visited. He mentions many times meeting Alexander Ramsey and members of his family in Washington and Philadelphia. Neill traveled East, in part, to obtain funds and teachers for Baldwin School in St. Paul.

Letters document Neill's chaplaincies with the First Minnesota Regiment (1861-1862) and at the South Street Military Hospital, Philadelphia (1862-1863). Letters, especially for January to April 1862 document activities of the First Regiment in Maryland and Virginia, including troop movements, visits to hospitals, the popularity of General McClellan, family news, some mention of battles and officers of the First Minnesota, particularly Dr. John Murphy, Colonel Dana and General Gorman. Beginning in January 1864 the letters document his service as one of President Abraham Lincoln's personal secretaries and his efforts to obtain a home in Washington, D.C. He purchased a farm in Beltville, Maryland.

Letters from 1865 to 1869 are few but include some from his cousin C. B. Duffield, who was a Confederate sympathizer. Letters from 1870 to 1893 relate to the employment of Neill's sons, Samuel and Henry, data on friends in Ireland, births, deaths, and marriages in the family, and also include a few letters from C.B. Duffield.

Letters in June 1893 describe Neill's visit to the Chicago World's Fair. Condolences upon the deaths of Edward Neill and his wife in 1893 and 1895 respectively include those from Newton H. Winchell, Charlotte O. Van Cleve, Mary E. and William G. LeDuc, William R. Marshall, and Matilda W. Rice. From 1900 to 1931 there are many letters written to Minnesota Neill, daughter of Edward, by her friends and relatives. Most relate to family matters and news of mutual friends. Letters in 1906 and 1909 from William Watts Folwell and Warren Upham concern preservation of the papers of Neill and transfer of papers to the Minnesota Historical Society.

Copies of manuscripts from French, Canadian, and English repositories; includes translations of Lahontan's Journal, George A. Belcourt's report on Hudson's Bay, and the Penicaut Journal. The last folder in the French and Canadian section contains miscellaneous translations of letters and reports, arranged chronologically (1683-1797). The final folder contains documents relating to England and to the English colonization of America, arranged chronologically (1607-1768).

Sermons, articles, memoirs, and similar data prepared by Neill. The first folder contains dated material; the last three folders are undated. Each undated document has been given a sequential number (1-30, inclusive) that is bracketed in the upper right hand corner of the manuscript. The manuscript President Lincoln's Mailbag is number 18 (See Abraham Lincoln and His Mailbag, edited by Theodore C. Blegen, St. Paul, 1964).

Includes data on the Neill family, the Civil War, religion, American history, and Neill's death in 1893.

Includes calling cards of Neill family members, brochures of Baldwin School and Macalester College, sample of Confederate money (1861), religious tracts, wedding invitations, commencement programs, and similar data. Items of particular interest include Historical Notes on the Ancestry and Descendants of Henry Neill, M.D. (1886) and poems by William Bronson LeDuc (1890?).

Images include Neill family members, as well as family friends and relatives.