The pipeline would be the latest piece of cross-border infrastructure that ties the U.S., Canada and Mexico together, all as importers and exporters of energy.
"It's not only very significant in terms of actual energy trade but it [Keystone] is very symbolic though in radically different ways to U.S.-Canadian trade relations and to the environmental community," said Daniel Yergin, vice chairman of IHS Markit.
"The unbuilt Keystone pipeline achieved the unique status of becoming the most famous pipeline in the world even though it is not completed," he said.
Absent the pipeline, Canadian producers would be forced to send more crude by rail as they also work on getting alternative pipelines heading to Canada's east and west coasts. Canada has the third largest proven reserves in the world after Saudi Arabia and Venezuela.
Regardless of what happens with the North American Free Trade Agreement, the U.S., Canada and Mexico have energy ties that transcend borders and go back decades.
The three countries have intentionally worked to combine the advantages of their energy resources. Viewed as friendly to the energy sector, there are still questions about whether the Trump administration could enact changes that affect the intricate web of energy connections between the three countries. The Republican Congress has already proposed a border tax that could complicate the situation, if approved.
While still seen as a low probability, the border adjustment tax would tax all imports at the border and exports would not be taxed at all. At the proposed corporate tax rate of 20 percent, a number of analysts say the border tax would be expected to make U.S. crude more expensive than international Brent.
Goldman Sachs analysts projected that gasoline prices would jump as a result by about 30 cents per gallon. The analysts said the dollar could adjust and move higher over time, reducing the impact.
"It's not so simple to say we're going to renegotiate the trade deals. We set up the system to create those inter-linkages. You just can't overnight legislate or executive order that away. If you try to do that, it's going to have negative economic impacts, not just for the economies on the border but for these specific industries, like energy," said Scott Anderson, chief economist at Bank of the West, in an interview last month.
Trump's selection of former Texas Gov. Rick Perry as energy secretary is seen as a positive for the oil and gas industry. Perry has spoken favorably about North America as a integrated energy powerhouse, including Mexico and Canada.
Perhaps one of the most surprising recent developments is the boom in U.S. natural gas that's flowing across the southern border, and the ambitious plans by the Mexican government to build more pipelines to take U.S. natural gas throughout Mexico and as far as Mexico City.
"Mexico has become a very important market for U.S. gas producers and without it, we'd be looking at lower prices," said Yergin. U.S. producers, grappling with low prices and record winter supply, would have to cap even more wells if it weren't for the growing demand from Mexico, which now accounts for about 5 percent of U.S. natural gas output.
The energy picture changed dramatically for North America in the last decade. The push by the U.S. energy industry into hydraulic fracking and horizontal drilling unleashed an energy boom, making the U.S. the world's biggest producer of natural gas and placing it firmly among the top three oil producers.
That has changed the situation for all of North America, at a time when Mexico's oil and gas output was in decline and Canada found some of its potential crude output landlocked. The ties between the three countries go way back. In the early 1900s, the U.S. began sharing electricity with its neighbors, and Canada is now a significant net exporter of electricity to the U.S.
One catalyst has been Mexico's program of energy reform, intended to break the hold of state-owned Pemex on its industry and bring new private investment to Mexico's energy industry. The decline in big part was due to a lack of investment by the government in Petroleos Mexicanos, and its increasing reliance on Pemex's revenue stream for its own budget.
"Before shale, the U.S. was importing a lot more gas from Canada," said Anthony Yuen, global energy analyst at Citigroup, in a recent interview. The U.S. was also worried not that long ago that it would need to import LNG, liquefied natural gas. But the shale boom changed everything.
Yuen said Canadian gas is still important to the U.S. West Coast, the Midwest and New England, in part because pipelines don't carry U.S. gas to those areas. Gas imports from Canada fluctuate based on weather, and can go from 5 billion to 7 billion cubic feet a day, he said.