Daniel J. Hennessy was born in Frederickton, New Brunswick, Canada, in September 1854. After leaving school at the age of 13 he worked at a grocery store and later a dry goods store. In 1879 he moved to Montana Territory and settled in Butte where he worked for the E.L. Bonner and Company store under the management of Michael J. Connell. In 1886 he opened his own store, across the corner of Main and Granite from his old employer. In 1889 it was incorporated as the D.J. Hennessy Mercantile Company. In about 1900 the Company built a large new store, which became the most complete department store in the northwest, and operated in close conjunction with the Anaconda Copper Mining Company. After Hennessy's death on January 27, 1908, the business was reorganized with part of the business continuing under the name Hennessy Mercantile Company, and a new holding company called The Hennessy Company being formed to acquire other stores and conduct a wider business. Eventually the Hennessy Mercantile Company expired. In the early 1910s all of the stock of The Hennessy Company was acquired by H.B. Claflin and Company of New York, a mercantile holding company. In 1914 this company went bankrupt and in doing so wrote notes on the assets of the Hennessy Company. To protect the Butte business, local manager C.J. Kelly got himself appointed receiver of the company and of Claflin's other Butte area stores; the M.J. Connell Company, the Copper City Commercial Company, and the MacCallum and Cloutier Mercantile Company. After the receivership closed in April 1915, these companies continued to be administered by Hennessy's.

Around 1890 Michael J. Connell reorganized E.L. Bonner and Company under his own name and in 1892 incorporated as the M.J. Connell Company. After M.J. Connell left Montana, Daniel Coleman took over management of the store. In 1914 as part of the Hennessy receivership the store effectively merged with Hennessy's. In January 1924 the merger became formalized and Connell's went out of business.

To serve the Anaconda Copper Mining Company's smelter town of Anaconda, D.J. Hennessy opened a branch there in 1890. Around 1894 the name was changed to the Copper City Commercial Company. This company, and its rival the MacCallum and Cloutier Mercantile Company (opened in 1887 by A.C. MacCallum, Charles A. MacCallum, and Augustin P. Cloutier and incorporated in 1902), were both merged into the Hennessy Company as a result of the receivership.

The Butte Wholesale Grocery Company was founded in August 1905 by James S. Casey, Charles E. Virden, A.P. Henningsen, and others. During the 1910s the company was operated as part of the Hennessy Company. On December 31, 1923, Hennessy's sold its interest in the Company to the Ryan Wholesale Company. Its name was changed in 1935 to the Ryan-Butte Company, and in 1959 to the Ryan Grocery Company.

Nothing is known about the Dominant Motor Company except that it operated an automobile and truck business at 55 West Granite in Butte, during the late 1910s. It was not formally incorporated.