US President Donald Trump signed an executive order on Thursday renaming Lake Ontario — one of the five Great Lakes straddling the US-Canadian border — as "Lake America", declaring the change "official, effective immediately" during a signing ceremony in the Oval Office. The move came days after trade talks between Washington and Ottawa collapsed, following the imposition of new 50% US tariffs on roughly $20 billion worth of Canadian goods. Canada has announced equivalent counter-tariffs in response.

Lake Ontario, the smallest of the Great Lakes by surface area, borders the Canadian province of Ontario and the US state of New York. Its name, like those of Lakes Huron, Michigan, and Erie, derives from an Indigenous word — in this case meaning roughly "the lake is beautiful" or "great lake." The executive order directs the US Department of the Interior to update the lake's designation in the Geographic Names Information Service, the official federal repository for domestic place names, within 30 days. The order's text offers a pointed justification: that the lake's deepest point lies on the American side, meaning the US "claims the largest portion of the lake's volume." Trump also mused publicly about further renaming, suggesting the Atlantic and Pacific oceans could be next: "We have a gulf and we have a lake. Now all we need is an ocean."

Canadian officials swiftly rejected the move. Prime Minister Mark Carney noted that the name Ontario predates both Canadian Confederation and the US Declaration of Independence by centuries, writing on social media that "this lake is called Lake Ontario — today and forever." Ontario Premier Doug Ford and Nova Scotia Premier Tim Houston echoed that position, with Houston calling it "real foolishness." New York Governor Kathy Hochul said her state, the only US state bordering the lake, "won't be calling it" Lake America. Within the US Congress, Democratic lawmakers also pushed back sharply, with Michigan Representative Debbie Dingell announcing plans to introduce legislation nullifying the order and describing it as "idiotic."

The renaming follows Trump's January 2025 executive order changing the Gulf of Mexico to the Gulf of America — a move rejected by Mexico, which argued that one country cannot unilaterally rename a shared international body of water. That precedent sparked a legal dispute with Google after the tech company updated its Maps platform to reflect the new name for US users. There is no internationally recognised body with authority over the naming of shared waters, meaning Canada is under no obligation to adopt the change.

Despite the heated symbolism, there were cautious signs that trade negotiations could eventually resume. Canadian trade minister Dominic LeBlanc noted that the US had withdrawn demands around French-language labelling requirements and confirmed that measures to protect Canadian culture would not be subject to future trade actions, saying his government looked forward to "further constructive US clarifications" that could open the door to "a mutually beneficial trade agreement that respects Canadian sovereignty." The name change, widely seen as a provocation rather than a substantive policy shift, underscores how sharply relations between the two long-standing allies have deteriorated — even as both sides leave a diplomatic off-ramp open.