1949 — Trans-Northern Pipelines Inc. is incorporated
1950s — Construction begins on the Ontario to Quebec including the Ottawa lateral pipeline and transportation of refined petroleum products begins; additional pumping stations are added to increase the capacity of the pipeline
1960s — A new branch line extends the Ontario-Quebec pipeline to Montreal’s Pierre Trudeau International Airport
1970s — Construction begins on the Alberta pipeline connecting refineries in the Edmonton area with facilities in Calgary; the Ontario-Quebec pipeline is extended with branches to Pearson International Airport and Montreal’s Mirabel Airport as well as an extension to connect to refineries in Nanticoke, Ontario, bringing the pipeline to its current length of 850 kilometres
1980s — Flow of products along the Ontario-Quebec pipeline is reversed in the eastern part of the pipeline to enable movement from Toronto-area refineries eastward to Montreal
2000s — TNPI celebrates 50 years of operation; an additional section of the Ontario-Quebec pipeline is reversed, linking refineries in Montreal westward to Toronto distribution terminals
2010 onwards — the Alberta pipeline marks 40 years of operation and TNPI marks 60 years of operation