Manuscripts, legal documents, notes and clippings pertaining to the life of William Milnor Roberts. Included are: four manuscript autobiographies written by Roberts between 1857 and 1874; biographical essays prepared by his sons, Milnor Roberts and Thomas Roberts; genealogical notes; a legal account of the Roberts estate in 1881; an applications for membership in professional societies that required vita information submitted by Roberts.

Professional and personal letters written or received by William Milnor Roberts or his son, Milnor Roberts. Correspondents include people associated with the engineering projects in which Roberts was engaged. Of particular note are: letters written by Roberts to his wife, Adeline DeBeelen Roberts, during his 1869 reconnaissance of the Northern Pacific Railroad route through Washington, Idaho, and Montana; a file of letters on engineering matters written to Henry S. Drinker; letters pertaining to Roberts's work in Brazil during both of his visits there.

Personal diaries, travel logs, and engineering notes compiled by William Milnor Roberts throughout the latter part of his life. Some volumes are personal diaries, recording Roberts's daily activities and impressions of people, places, and events. Other logs and notes are more professionally oriented, recording Roberts's observations of landscapes, geographic features, and engineering problems. Occasionally the personal and professional writings overlap, and both were likely used by Roberts to compile his lengthy written reports and essays, housed in Series 5. The journals document Roberts's travels in the western United States--especially the northwest--as well as Europe and Brazil. Notes in box 5, folders 6-9 are either unidentified or memoranda Roberts recorded from his readings.

Membership certificates, professional credentials, and legal documents pertaining to William Milnor Roberts or his son, Milnor Roberts. Included are testimonial letters written by former employers and professional colleagues prior to Roberts's departure for Brazil in 1857.

This series consists of manuscript reports and report drafts prepared by William Milnor Roberts and regarding the various engineering projects on which he worked. Many of the reports were later published in booklet and pamphlet form and have been retained in Series 6. The reports in this series cover every major engineering project on which Roberts worked during the latter portion of his career, including those in Brazil and those undertaken for the Northern Pacific Railroad. Also included are essays of a more general nature that Roberts wrote, such as life in Brazil, the nature of gravity, and American government.

This series contains newspaper clippings, books, and printed reports created or collected by William Milnor Roberts. Newspaper clippings include entire issues of American and Brazilian newspapers that contain articles dealing with either engineering projects or Roberts family matters. Clippings from unidentified newspapers have been sorted by topics. Printed reports make up the bulk of this series and are almost entirely written by Roberts. They have been arranged chronologically and listed with their full titles in the inventory. Printed ephemera, such as broadsides, business cards, and menus, are also included.

This series includes portrait photographs of William Milnor Roberts, group photographs of Roberts with colleagues, family photographs, and watercolor paintings of Brazil. The portraits include images of Roberts from the 1860s-1880s as well as the image published in the in 1940. Group photographs show the Northern Pacific Railway survey party and engineers. Others pictured include George Stark, J. B. Eads, and Eleanor Roberts Baltzell. There are also several taken or collected in Brazil as well as images of Roberts Hall, Montana State College (now Montana State University). The watercolors date from the 1870s and depict a church and the Paulo Alfonso waterfall.