The Sault Ste. Marie Museum is a non-profit, charitable organization facilitated by the Sault Ste. Marie & 49th Field Regiment R.C.A. Historical Society for the citizens of Sault Ste. Marie and the District of Algoma, as well as visitors to the community. A management Board of Directors oversees the operation of the Museum.

On August 10th, 1920, an organizational meeting was held attended by twelve interested members of the community. At a subsequent meeting held on August 17, 1920, in the council chambers of City Hall, a constitution was adopted and a slate of officers elected.

On October 31st, 1921, the Sault Ste. Marie Historical Society became incorporated through affiliation and membership with the Ontario Historical Society.

On January 26th, 1951 Lt. Col. Derrer had persuaded the Department of Defense to approve the exclusive use of a room in the Pine St. Armoury for a library / museum. Subsequently, a meeting held in the council chambers of City Hall, led by original members of the Society, led to amalgamation of the Sault Ste. Marie Historical Society and the Regimental Historical Society.

Although the Department of Defense had allocated space for the museum, the Society was responsible for its furnishings. Sir James Dunn, then president of Algoma Steel, furnished it handsomely in all details. In 1956 a part time curator was hired. However, over time the physical limitations of the space became acute, added to which access by the public was difficult.

In 1980, with the introduction of museum standards by the Ontario Ministry of Culture and Recreation as a requirement for funding, the need to find alternative space became imperative.
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The “Old Post Office” building which the museum currently occupies was identified as the most promising site. The municipality of Sault Ste. Marie purchased the building in 1981.

In 1982 an agreement was recorded between the 49th Field Regiment R.C.A. and the Sault Ste. Marie and 49th Field Regiment R.C.A. Historical Society regarding their continuing collaboration. The agreement recognizes the debt owed to the Regiment by the Society for providing space in the Armoury, and states the intention of the Society to relocate to the new facility. Also included are the terms of ownership and loans for the military artifacts and papers pertaining to military history that would be transferred to the new museum.
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The museum was opened in 1983 by the Society under an agreement with the City of Sault Ste. Marie for the use of the building.