Earlier this month, President Trump initiated tariffs on trade with Canada, China, and Mexico. News headlines have been dominated since then by announcements of retaliatory tariffs, increases to planned tariffs, and other economic actions. The most recent of these declarations include a 25% surcharge on power coming from Ontario, the threat of a complete cut-off of all power from Ontario to the U.S., and President Trump’s instruction via social media to double steel and aluminum tariffs on Canada to 50%—all of which has been paused as of March 11th. However, all of these announcements, and their subsequent rollback, raise several important questions, like how intertwined are these two nations’ electrical grids, just how reliant is the U.S. on Canadian power, and where is this dynamic most impactful?
Looking at the past two years of power transmission between the United States and Canada, Canadian generation has consistently been used to meet American power demands, especially in the Northeast. Already in 2025, transmission from Hydro-Québec TransÉnergie (HQT) to ISO New England (ISO-NE) has hit a two-year high of 2,238 MW, and transmission from Ontario’s Independent Electricity System Operator (IESO) to New York ISO (NYISO) also hit a two-year high of 2,311 MW. There have only been two meaningful exceptions to this dynamic: the first exception occurs when HQT occasionally receives power from NYISO to meet the power demands of metropolitan hubs like Toronto, Montreal, and Ottawa; the second exception occurred between New Brunswick System Operator (NBSO) and ISO-NE when the Point Lepreau Nuclear Power Plant was temporarily shut down for maintenance between early April and mid-December of 2024.
The U.S. Northeast’s dependence on Canadian power can also be observed through Canadian power imports relative to the load on an ISO’s grid. As seen below, relative imports show the strong reliance that ISO-NE has on Canadian power. Both ISO-NE and NYISO’s usage, as a percentage of load of Canadian generation sources, peaked in 2023; ISO-NE and NYISO reached a 10-day average of nearly 18% and about 12%, respectively, with their intraday peaks reaching as high as 21% and 17%, respectively. Similar peaks were reached again in 2025, when the only time the 10-day average did not indicate any noticeable power transmission into the U.S. was during the anomaly outage at the Point Lepreau Nuclear Power Plant mentioned above.
Although the U.S. Northeast is already heavily dependent on Canadian generation, it’s clear the region intends to continue relying on Canadian power to meet its power demand. This is evidenced by the ongoing construction of four new transmission lines, which would bring at least a 55% increase in Canadian-NYISO transmission capacity alone.
Regardless of whether tariffs or surcharges are ultimately implemented, the energy sector will surely continue to brace for the unexpected as global politics and international trade remain turbulent. Will power tariffs and surcharges wipe away the benefits of planned infrastructure buildout? Could trade disputes affect the development of planned transmission lines? Check back for additional energy Insights as the North American energy landscape continues to develop.
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