Charles William Gross was born in 1880. He worked for the Great Northern Railway Company as an assistant materials clerk in the company's Dakota Division from 1906 to 1907, and as a traveling claim agent from 1914 to 1917. From 1917 until 1923 Gross was chief clerk of the Chicago, Milwaukee and St. Paul Railway Company in Three Forks, Montana. In 1923 he was hired as field auditor by the Montana Board of Equalization to monitor the production of crude oil throughout the state. He was promoted to assistant secretary in 1924. The following year he resigned and moved to Fort Myers, Florida, but returned in 1926 to work as a general accountant for William B. Finley, a Great Falls certified public accountant, and later that year for James A. Johnson in Shelby.

In 1927 Gross was hired as assistant supervisor of oil and gas wells by the Board of Railroad Commissioners, and by 1930 was supervisor of the Gasoline Licensing Division of the Public Service Commission. From 1933 to 1943 Gross was employed by the Independent Refining Company of Billings, but returned to Helena in 1943 to work for the Board of Equalization. He remained with the Board until his death on October 4, 1950. C.W. Gross purchased stock in the Nashua Oil and Gas Company of Nashua, Montana, in 1930, and in 1931 was elected secretary of the Montana Division of the Independent Petroleum Association of America. The Nashua Oil and Gas Company was incorporated in Nashua, Montana, on February 28, 1923, by N.A. Sampson, A. Torkelson, E.T. Peterson, Arthur Lee, and A.N. Currie.