The Canadian National Railway Company was responsible for consolidating the railways, works and activities of the Canadian Northern System, the Canadian Government Railways, and all other lines that were entrusted to it by Order in Council and operating them together as a national railway system. The Governor in Council nominated the Board of Directors and the stock was vested in the Minister of Finance. This changed briefly in 1932 after the Royal Commission on Transportation made recommendation to the Canadian Government that three Trustees be appointed by the Governor in Council, in whom should be vested all the powers of the Board of Directors. The recommendations were implemented by the passage of the Canadian National-Canadian Pacific Act 1933 (Act 23-24, Geo. V, Cap. 33) on May 23, 1933. The Board of Directors vacated under Order in Council P.C. 2682 dated December 23, 1933 and the appointed Trustees assumed office on December 30, 1933. Following a change of Government after the General Election of 1936, the Trustee system was abolished and the Governor in Council appointed a Board of Directors to assume the duties it once had.

In addition to operating a railway system, the Canadian National Railway Company also operated express services, a telegraph company, a chain of hotels, and a steamship line. In 1923, the Company established the first radio network in North America, which later became the basis for the Canadian Broadcasting Corporation. The radio network broadcast across eight radio stations located throughout the country, and was capable of being received by train passengers through headsets aboard specially equipped train cars.

In 1937, the Canadian government established a national airline known as TransCanada Air Lines (TCA) and made it a subsidiary of the Canadian National Railway Company. Several decades later, TCA was renamed Air Canada and in 1977 it became a separate company.

In 1968 the Canadian National Railway Company, now commonly known as CN, created an international consulting division known as CANAC Consultants Limited Incorporated (CANAC). CANAC, a joint undertaking between Canadian National and Air Canada, offered international consulting services in the areas of air and surface transportation.

In an attempt to revive the popularity of rail passenger services and lure travelers away from highways and airlines CN began to launch new services in the 1970s. In 1977 VIA Rail Canada Incorporated was established as a wholly owned subsidiary of CN, although it was to operate at arms length. On December 15, 1977 Parliament authorized the government to purchase all VIA shares from CN, thereby paving the way to make VIA a separate entity. In April 1978, VIA became a Crown Corporation and assumed responsibility for management of all CN and CP Rail passenger services, with the exception of commuter services.

During the 1980s, CN underwent further radical transformation as businesses in which it had an important presence for many years were divested. In 1986 the CN trucking firm was sold (P.C. 05/2469). Then in 1988 CN sold the CN Hotels (P.C. 0231), Northwestel Incorporated (P.C. 2476), and Terra Nova Tel (P.C. 2477). In that same year CN also sold off its fifty per cent share in CNCP Telecommunications (P.C. 2787) and terminated railway service in Newfoundland (P.C. 2295). A decision was made to divest all of these properties in order to help to reduce the Company's debt and thus strengthen its financial position.

Following the Company's privatization in 1995, CN sold the oil and gas assets of its CN Exploration business unit and certain real estate assets of the discontinued CN Real Estate unit to third parties. The Company's remaining non-rail real estate business, including the CN Tower in Toronto, was transferred to the Government of Canada. Today the Canadian National Railway Company operates as a private sector freight railway spanning Canada and mid-America from the Atlantic and Pacific oceans to the Gulf of Mexico.

The predecessors to the Canadian National Railway Company were the Canadian Northern Railway and the Canadian Government Railway. In 1917, the Government of Canada gained control of the Canadian Northern Railway system and the following year Dominion Order in Council P.C. 2854 placed the Canadian Government Railway system under the Board of Directors of the Canadian Northern Railway for operation and management. Under Dominion Order in Council P.C. 3122 dated December 20, 1918, the use of the name Canadian National Railways was authorized to designate the operation procedures of the Canadian Northern Railway Company and the Canadian Government Railways. Then on June 6, 1919, Parliament passed an act to incorporate the Canadian National Railway Company Limited.

On October 4, 1922, the Board of Directors of the Canadian National Railway Company was appointed the Board of Directors of the Grand Trunk Railway Company of Canada. By an agreement between Canadian National Railway Company and the Grand Trunk Railway Company of Canada, which was sanctioned by Dominion Order-In-Council P.C. 181 dated January 30, 1923, the Grand Trunk Railway Company of Canada was amalgamated with Canadian National Railway Company to form one company under the latter name. The Head Office of the Canadian National Railway Company was declared to be in Montreal, Quebec.

Prior to privatization, Canadian National Railway Company operations were divided into five regions: Mountain, Prairie, Great Lakes, St. Lawrence, Atlantic and Newfoundland. In 1985, the Prairie and Mountain Regions were combined to form the Western Canada division with its head office located in Edmonton, Alberta. After the Company was privatized the operations were divided into three regions: Western Canada, Eastern Canada and United States.

Past presidents of Canadian National Railway Company:
David B. Hanna (1919-1922)
Sir Henry Thornton (1922-1932)
Samuel J. Hungerford (1932-1941)
Robert Charles Vaughan (1941-1949)
Donald Gordon (1950-1966)
Norman J. MacMillan (1967-1974)
Robert A. Bandeen (1974-1982)
Maurice LeClair (1982-1986)
Ronald E. Lawless (1987-1992)
Paul M. Tellier (1992-2002)
E. Hunter Harrison (2003- )