More than 3,000 kilometres (1,900 mi) of the system is in the United States while the rest is in Canada and serves the Athabasca oil sands production facilities.
It crossed approximately 1,600 kilometres (990 mi) from Redwater, Alberta, through Saskatchewan, Manitoba, North Dakota, and Minnesota, to the Great Lakes seaport of Superior, Wisconsin.
[3][4] Because the lakes froze in the winter, preventing tanker traffic, the decision was soon made to expand the pipeline all the way to Sarnia.
From there, Line 5 runs through the Upper Peninsula of Michigan and across the straits of Mackinac to cross back into Canada at the St. Clair River.
[14] Deliberations over construction of a new Line 3 pipeline have drawn resistance from climate justice organizers and Native communities in Minnesota.
[15] On July 4, 2002, 252,000 gallons of crude oil spilled into a marsh near Cohasset, Minnesota due to a rupture of Line 4 running from Edmonton, Alberta, Canada, and Superior, Wisconsin.
[17] On July 26, 2010, 840,000 gallons of dilbit crude oil leaked from the pipeline in Calhoun County, Michigan, spilling into Talmadge Creek that flows into the Kalamazoo River.
[18][19] Despite alarms at Edmonton headquarters it took eighteen hours and a report from a Michigan utilities employee before the pipeline company acted to halt the flow finally.
[20] In addition, the company was fined $3.7 million by the United States Department of Transportation due to 24 violations in pipeline safety regulation.
[23] In 2018, a tugboat dropped its anchor on the pipeline near the Straits of Mackinac in Michigan, denting the pipe and causing 600 gallons (2,270 liters) of mineral oil to leak from two electric cables.
[27] It was detected during a routine check of the Cambridge station when "an Enbridge Technician noticed what appeared to be product staining an area of gravel" near a discharge valve, according to a report on the incident by the Federal Hazardous Materials Safety Administration.