Hubert Alfred (H.A.) Simmons was born in Spadra, Arkansas, the son of Ferdinand Simmons, on November 13, 1881. Simmons moved to Red Lodge, Montana, in 1899, where he worked in local coal mines and for the Montana Mercantile Co. He left Red Lodge to attend the University of Indiana Law School from which he graduated in 1906; he was admitted to the Montana Bar that same year. In 1906 Simmons, a Republican, was elected clerk of the district court, and he held that position through 1916, when he was elected Carbon County attorney. He held that post until 1920, when he began a twelve-year term as Red Lodge city attorney. In the years following World War I, Simmons was accused of being a member of the local Liberty Committee, a vigilante group established to police political non-conformists. Simmons denied the charges, and in 1932 was elected to the Montana state senate; he ran successfully for that office seven times. In his capacity as a legislator, Simmons was an advocate for the construction of the Beartooth Highway to connect Red Lodge with Cooke City and create a northeastern entrance to Yellowstone National Park. In 1928 Simmons was the chairman of the Hoover-Curtis Volunteer Committee of Carbon County, part of the statewide campaign for presidential candidate Herbert Hoover.

On June 1, 1907, Hubert Simmons married Ellen Freeman, daughter of William R. Freeman, and sister of James M. and William R. Freeman, Jr., both of whom were owner-operators of the Montana Coal and Iron Company of Washoe. The couple had a son, Hubert A., Jr. (born, February 10, 1910; died, 1976); and twin daughters, Helen Annie and Margaret (born, April 20, 1918). Ellen Simmons died on March 24, 1940, and Simmons married Mrs. Dorothy Chase Denison on June 14, 1940. During the Second World War Helen served as a clerk-typist in the U.S. Marine Corps, stationed primarily in Charleston, South Carolina. She enlisted in Butte on March 16, 1944, and was honorably discharged on August 21, 1946, having obtained the rank of sergeant. In addition to his political activities, H.A. Simmons maintained a law office in Red Lodge. He was joined in his practice by his son in May 1937.

Simmons also invested in various coal mining and distribution firms, including the Eagle Coal Company, the Owl Mining Company, W.B. Innes and; Co., and the Western States Coal Company. The Eagle Coal Company was established in December 1918 by T.E. Frasure, and John T. Flaherty and his brother J.V. Flaherty, all of Red Lodge, to operate the Foster coal mining claims in the Bearcreek-Foster Gulch area of Carbon County. The Flahertys were brothers-in-law of James M. Freeman. The company office was located in the U.S. National Bank Building in Red Lodge. In March 1919, H.A. Simmons bought some of the company's stock. The company actively mined and sold coal through the 1920s. By the 1930s much of the company's mine management and sales had come under the auspices of the Montana Coal and Iron Company. On June 30, 1938, that company formally took over the management, ownership, and interest of the Eagle Coal Company, which continued to produce coal for some additional years. The company was officially dissolved on December 31, 1947.

The Western States Coal Company was established on September 18, 1917, as a coal distributor. The firm's stockholders included John T. Flaherty, H.A. and Ellen Simmons, and E.A. Logan, all of Red Lodge. The company also owned stock in the Eagle Coal Company. At their annual meeting in January 1920, the stockholders voted to discontinue business and transfer all its liabilities and assets to H.A. Simmons.

W.B. Innes and Co. was incorporated in March 1919 as the general sales agent for the Eagle Coal Company and other firms. Stockholders included Walter B. and M.C. Innes of Billings and H.A. and Ellen Simmons, and Charlott Dilworth of Red Lodge. Walter B. Innes served as the district fuel administration for all of Montana and parts of Wyoming during the First World War, and as secretary of the Western Coal Producers' Association. The firm, headquartered in the Electric Building in Billings, operated through 1922, when its accounts were assigned to Montana Coal and Iron Company.

The Owl Mining Company was incorporated in Idaho to develop mining claims near Shoup, Lemhi County, Idaho. The original officers of the company were J.M. Freeman, Billings; E.H. Casterlin, Salmon, Idaho; and H.A. Simmons. Some development work was done on the claims during the 1930s, but for most of its existence, the company's mines were nonproductive.

H.A. Simmons was a member of the Methodist Church, Rotary Club, the Inquiry Club and the Masons. In the early 1940s Simmons was involved in the formation of the Carbon County Pioneers' Association, a group composed of men and women who became residents of Carbon County prior to 1901. The group incorporated in 1942, and Simmons was elected its president. H.A. Simmons died on December 14, 1967, in Red Lodge, at the age of 86.