While there is some debate on the exact meaning of "Sault" in Sault Ste. Marie, scholars of early French note that the word translates into jump, referring to the place where one needs to "jump", or put into the St. Mary’s River. This translation relates to the treacherous rapids and cascades that fall over 20 feet from the level of Lake Superior to the level of the lower lakes. Hundreds of years ago, this prohibited boat traffic and necessitated an overland portage from one lake to the other. Thus the entire name translates to "Saint Mary's Rapids" or "Saint Mary's Falls". Although the word sault is pronounced "so" in French, it is pronounced like "soo" (suː) in the English pronunciation of the city name. Residents of the city are called Saultites.
Sault Ste. Marie is bordered to the east by the Rankin and Garden River First Nation reserves, and to the west by Prince Township. To the north, the city is bordered by an unincorporated portion of Algoma District, which includes the local services boards of Aweres, Batchawana Bay, Goulais and District, Peace Tree and Searchmont.
The city's census agglomeration, including the townships of Laird, Prince and Macdonald, Meredith and Aberdeen Additional and the First Nations reserves of Garden River and Rankin, had a total population of 79,800 in 2011.
Sault Ste. Marie is the seat of the Algoma District.
To the south, across the river, is the United States and the city of Sault Ste. Marie, Michigan. The two cities are joined by the International Bridge, which connects Interstate 75 on the Michigan side and Huron Street (and former Ontario Secondary Highway 550B) on the Ontario side. Shipping traffic in the Great Lakes system bypasses the Saint Mary's Rapids via the American Soo Locks, the world's busiest canal in terms of tonnage that passes through it, while smaller recreational and tour boats use the Canadian Sault Ste. Marie Canal.
This area was originally called Baawitigong, meaning "place of the rapids," by the Ojibwa, who used the site as a regional meeting place during whitefish season in the St. Mary's Rapids. (The anglicized form of this name, Bawating, continues to be used in institutional and geographic names in the area.)
After the visit of Étienne Brûlé in 1623, the French called it "Sault de Gaston" in honour of Gaston, Duke of Orléans, the brother of King Louis XIII of France. In 1668, French Jesuit missionaries renamed it Sault Sainte Marie, and established a settlement (present-day Sault Ste. Marie, Michigan) on the river's south bank. Later, a fur trading post was established and the settlement expanded to include both sides of the river. Sault Ste. Marie one of the oldest French settlements in North America. It was at the crossroads of the 3,000-mile fur trade route, which stretched from Montreal to Sault Ste. Marie and to the North country above Lake Superior. A mixed population of Europeans, Native Americans and First Nations peoples, and Métis lived at the village spanning the river.
The city name originates from Saults de Sainte-Marie, archaic French for "Saint Mary's Falls", a reference to the rapids of Saint Marys River. Etymologically, the word sault comes from an archaic spelling of saut (from sauter), which translates most accurately in this usage to the English word, cataract. This in turn derives from the French word for "leap" or "jump" (similar to somersault). Citations dating back to 1600 use the sault spelling to mean a cataract, waterfall or rapids. In modern French, however, the words chutes or rapides are more usual, and sault survives almost exclusively in geographic names dating from the 17th century. (See also Long Sault, Ontario, Sault St. Louis, Quebec, and Grand Falls/Grand-Sault, New Brunswick, three other place names where "sault" also carries this meaning.)
On July 20, 1814 an American force destroyed the North West Company depot on the north shore of the St. Marys River. Since the Americans were unable to capture Fort Michilimackinac, the British forces retained control of the Sault Ste. Marie.
In 1870, the United States refused the steamer Chicona, carrying Colonel Garnet Wolseley permission to pass through the locks at Sault Ste Marie. The Wolseley Expedition incident led to the construction of a Canadian Sault Ste. Marie Canal, which was completed in 1895.
Sault Ste. Marie, Ontario was incorporated as a town in 1887 and a city in 1912. The town gained brief international notoriety in 1911 in the case of Angelina Napolitano, the first person in Canada to use the battered woman defence for murder.
During World War II, and particularly after the US was attacked at Pearl Harbor in 1941, concern turned to the locks and shipping channel at Sault Ste. Marie. A substantial military presence was established to protect the locks from a possible attack by Nazi German aircraft from the north. The new development of long-range bombers created fears of a sudden air raid. Military strategists studied polar projection maps which indicate that the air distance from occupied Norway to the town was about the same as the distance from Norway to New York. That direct route of about 3000 miles is over terrain where there were few observers and long winter nights.
A joint Canadian and US committee called the "Permanent Joint Board on Defence" drove the installation of anti-aircraft defence and associated units of the United States Army Air Forces and Royal Canadian Air Force to defend the locks. An anti-aircraft training facility was established north of Sault Ste. Marie on the shores of Lake Superior. Barrage balloons were installed, and early warning radar bases were established at 5 locations in northern Ontario (Kapuskasing, Cochrane, Hearst, Armstrong (Thunder Bay District), and Nakina) to watch for incoming aircraft. Military personnel were established to guard sensitive parts of the transportation infrastructure. A little over one year later, in January 1943, most of these facilities and defences were deemed excessive and removed, save a reduced military base at Sault Ste. Marie.
On January 29, 1990, Sault Ste. Marie became a flashpoint in the Meech Lake Accord constitutional debate when council passed a resolution declaring English the city's official language and the sole language for provision of municipal services. The Sault Ste. Marie language resolution was not the first of its kind in Ontario, but because Sault Ste. Marie was the largest municipality to have passed such a resolution and the first to do so although it had a sizable Franco-Ontarian population, the council's action was very controversial. Many objections were raised by the French-speaking population.