The conflict over Enbridge’s Line 5, the pipeline that carries crude oil and natural gas from Alberta to Ontario through the United States, continues to pose great risks for both Canadians and Americans.

Recently, Michigan Governor Gretchen Whitmer’s commitment to shutdown the pipeline incurred another judicial setback—the court essentially ruled her actions were outside her authority. Her insistence on revoking the permit, which allows the pipeline to cross the Straits of Mackinac, compelled Ottawa to invoke (again) the 1977 Transit Pipelines Treaty allowing Canada’s federal government to bypass the Michigan governor and communicate directly with Washington to try to resolve the matter.

But what if Governor Whitmer successfully shuts down Line 5?

On the Canadian side, closing Line 5 would cause a shortage of at least 14 million gallons of gasoline per day and increase the costs of oil by roughly US$2.24 per barrel.

Consider, Line 5 stretches from Western Canada across Wisconsin and Michigan carrying 540,000 barrels of oil and natural gas liquids per day to Ontario’s four operating refineries in Sarnia, which is used to produce jet fuel, diesel, gasoline and petrochemicals. This operation generates nearly 29,000 direct and indirect jobs in Ontario and is critical for refining much of the jet fuel used at Pearson International Airport, the country’s busiest airport.

Line 9, which runs from Sarnia to Montreal, supplies about two-thirds of the crude oil refined and consumed in the province of Quebec. Any change to Line 5 will eventually affect Line 9, including operations at the Montréal-Trudeau and Jean Lesage airports.

South of the border, Line 5 provides 65 per cent of the propane used in the Upper Peninsula of Michigan and supplies refineries in Ohio, which produce about 42 per cent of Southeastern Michigan’s gasoline, diesel used in manufacturing, and the majority of jet fuel used at Detroit Metropolitan Airport. One consumer advocacy group estimated the economic losses from a shutdown of Line 5 at US$20.8 billion for just Michigan, Ohio, Indiana and Pennsylvania.

In fact, the “significant public and foreign policy implications” of shutting down Line 5 were highlighted recently by a Wisconsin judge who gave Enbridge five years to reroute the pipeline around the Bad River Band of the Lake Superior Tribe of Chippewa Indians territory.

Simply put, shutting down Line 5 will reduce the energy supply in both Canada and the U.S., lead to job losses and increase already high energy prices. Roughly 85 million people on both sides of the border would feel the negative impact of shuttering Line 5 if Governor Whitmer is successful.

Finally, Whitmer’s environmental concerns are not in line with the latest review by the U.S. Pipeline and Hazardous Materials Safety Administration, the federal regulator in charge of pipeline safety, which found no threat of leakage or safety issues with Line 5.

Closing Line 5 could, however, impose unintended environmental costs. The demand for the energy supplied by Line 5 will not disappear since both Ontarians, Quebecers and Americans in the region still require energy for home heating and transportation. To supply it, companies will likely resort to alternatives including rail and trucks that, according to a 2017 study, present a significantly higher risk of accidents than pipelines.

Line 5 remains the safest and most efficient way to deliver needed energy to the region. Closing it would have severe economic consequences for both Canadians and Americans without improving the environment.