At its 1923 merger into the Canadian National Railway (reporting mark CN), the CNoR owned a main line between Quebec City and Vancouver via Ottawa, Winnipeg, and Edmonton.

The network had its start in the independent branchlines that were being constructed in Manitoba in the 1880s and 1890s as a response to the monopoly exercised by Canadian Pacific Railway (CPR).

They also began building and buying lines south to connect with the U.S. border at Pembina, North Dakota, and east to Ontario.

CNoR's first step toward competing directly with CPR came at the start of the 20th century with the decision to build a line linking the Prairie Provinces with Lake Superior at the harbour in Port Arthur-Fort William (modern Thunder Bay, Ontario), which would permit the shipping of western grain to European markets as well as the transport of eastern Canadian goods to the West.

The Winnipeg-Port Arthur line was completed on December 30, 1901, with the last spike being driven just east of Atikokan station by Ontario's Commissioner of Crown Lands, Elihu Davis.

From a series of disconnected railways and charters, the network became 1,200 miles of profitable and continuous track that covered most of the prairies by 1902.

Throughout the 1890s, they reached Swan River, and continued building north between the Porcupine Hills to the west and Lake Winnipegosis to the east.

[6] Adding an equally costly route to supplement the existing uneconomical CP track through Ontario seemed more ludicrous.

Rather than competing with the GTPR in having a terminal at the mouth of the Skeena, the CNoR accepted BC government subsidies to switch to the Vancouver area.

CNoR's initial expansion in the 1890s and 1900s had been relatively frugal, largely by acquiring bankrupt companies or finishing failed construction projects.

[17] However, the largest costs were from building on "the wrong side" of the Thompson and Fraser rivers in the Coast Mountains of British Columbia.

The most infamous construction folly on the CNoR in British Columbia happened in 1913, when blasting for a passage for the railway at Hells Gate triggered an enormous landslide which partially blocked the narrow swift-flowing Fraser River.

[21] The last spike of the CNoR transcontinental railway was driven January 23, 1915, at Basque, British Columbia,[22] with Montreal-Vancouver freight and passenger services commencing six months later,[23] and providing a rail network in Nova Scotia, Southern Ontario, Minnesota, and on Vancouver Island.

CNoR was heavily indebted to banks and governments, and its profitable branchlines in the prairie provinces — "Canada's breadbasket" — would not generate enough revenue to cover construction costs in other areas.

On December 20, 1918, a Privy Council order directed CNoR and CGR to be managed under the name Canadian National Railway (CNR) as a means to simplify funding and operations, but CNoR and CGR would not formally merge and cease corporate existence until January 20, 1923, the date Parliament passed the final act to incorporate CNR.