Thomas Cruse was a Helena, Montana, miner, banker, and businessman. This collection (1841-1956) consists of incoming correspondence; legal and financial records; maps; reports; and miscellany. Records for Cruse's various enterprises are divided into nine subgroups including the Thomas Cruse Savings Bank; Thomas Cruse Estate; Thomas Cruse Mining and Development Company; etc.

John T. Murphy (1842-1914) was a Helena, Montana, merchant, rancher, banker, and mine investor. Collection (1865-1935) includes correspondence, financial records, legal documents and other material of Murphy, the Murphy Estate, and various companies he founded, including the Powder River Land and Cattle Company, Montana Cattle Company (Seventy-Nine Ranch), and the Murphy-Maclay Hardware Company.

Herbert Peet (1892-1959) was a Great Falls, Montana, newspaperman and amateur historian. Collection consists of research notes on Montana history copied from various sources; clippings; history articles; and Peet's writings, including a manuscript on Governor Samuel T. Hauser and a day-to-day chronicle of Hauser's career.