Thomas Larson operated a sheep ranch near Choteau, Montana, and served in the Montana legislature. Collection (1912-1948) includes correspondence, financial records, legal documents, speeches, and subject files.

Link and Haire, Architects, was a firm founded by J.G. Link and Charles Haire that designed public and private buildings throughout Montana, including jails, courthouses, schools, hotels, etc. Records (1904-1926) include correspondence about architectural jobs, Scottish Rite Freemasonry, and social life; court papers; and miscellany.

The Little Ben Mining Company was a Helena and Landusky, Montana, gold mining company, incorporated in 1932, to develop the Little Ben Quartz Lode which had been discovered in 1892. Records include general correspondence (1932-1945); financial records (1932-1945); legal documents, including an abstract of title (1892-1913); organizational materials (1932-1944) including minutes, stock books, etc.; and mint deposit reports (1933-1942).

Elizabeth Lochrie was a Butte, Montana, western artist. Collection (1916-1979) consists of correspondence, subject files, clippings, and memorabilia collected by Lochrie as source materials for her paintings.

Richard Lockey (1845-1924) was a Helena, Montana, bakery store owner, insurance agent, and real estate investor. Papers (1862-1924) include personal papers; bakery business records (1876-1883); real estate and insurance business records (1880-1922); Idaho property records (1884-1908); and miscellaneous smaller subgroups.

John Lucas was mine superintendent of the Granite-BiMetallic Consolidated Mining Company and other mining operations in the Philipsburg, Montana, area. Papers (1903-1916) include general correspondence with Paul A. Fusz, Charles D. McLure, and others about the operation of the mines. There are also materials on the Montana Democratic Party and the United Confederate Veterans.

Ranney Lyman (born 1880) was a cadastral surveyor in South Dakota and Montana for the U.S. General Land Office and its successor, the Bureau of Land Management. His papers consist of a biography (1954) and reminiscence (1970) by Lyman's wife Mabel Kelsey Lyman; general correspondence (1916-1953); survey diaries (1913-1950); financial records; and lists (1903-1949) of survey crew members.

The Madison State Bank was located in Virginia City, Montana. Collection includes records of that bank and of its predecessors Raymond, Harrington and Company (1879-1884), Hall, Harrington and Company (1884-1889), and Hall and Bennett (1889-1903). Records include journals (1879-1903), ledgers (1887-1919), and other financial records.

Martin Maginnis (1841-1919) was a Democratic Montana Territorial Delegate to Congress from 1872 to 1882; a member of the 1889 Montana Constitutional Convention; and newspaper publisher. Papers (1864-1912) consist primarily of incoming correspondence concerning politics; and outgoing correspondence, court papers, legal documents, and a scrapbook. Incoming correspondence includes typescript copies.