President Donald Trump signed an executive order Thursday afternoon directing federal agencies to rename Lake Ontario "Lake America," escalating a trade war with Canada that has already produced dueling 50% tariffs on billions of dollars of goods.

Trump signed the order in the Oval Office, telling reporters the change had been "something I've been thinking about for a long time." The order instructs the Interior Department to update official U.S. geographic databases and maps to reflect the new name for the Great Lake that forms part of the border between New York and Ontario, Canada.

"No message, as you know, Canada has been ripping us off for a long time on trade," Trump said, adding that "the United States doesn't expect to be doing much business with Ontario any longer."

Gulf of America, Round Two

The move mirrors Trump's 2025 executive order renaming the Gulf of Mexico the "Gulf of America" for federal purposes — a change that applies only to U.S. government references and cannot force Canada, international mapmakers, or anyone else to adopt the new name.

"If you think about it, we have a gulf and we have a lake. Now, all we need is an ocean."

Trump first floated the idea in an Aug. 25 Truth Social post, writing that "the United States is giving serious consideration to changing the name of Lake Ontario to Lake America" and that "Canada will be treated like a State no longer!"

The renaming lands amid a rapidly deteriorating trade relationship. Washington imposed 50% tariffs on hundreds of Canadian goods over the weekend, with a separate 50% levy on Canadian automotive and steel imports set to begin in January. Canada has vowed "dollar for dollar" retaliatory tariffs of up to 50% on U.S. imports, due to take effect Sept. 8, according to CBS News.

Canadian Prime Minister Mark Carney has promised to match the tariffs. Ontario Premier Doug Ford was blunter, calling Trump a "loser" and a "dictator" and insisting the lake "will always be Lake Ontario to all Canadians and the rest of the world," per ABC News. Canada's minister for U.S.-Canada trade, Dominic LeBlanc, brushed off the renaming, saying Ottawa had decided "not to respond to sort of the daily social media posts" from the White House.

Ford pledged to "fight with everything we have" as the two countries barrel toward the September tariff deadline.

Legally, Trump's order only binds U.S. federal agencies — it cannot compel Canada, international mapping bodies, or private cartographers to drop "Lake Ontario," the same limitation that has kept "Gulf of Mexico" in wide global use outside U.S. government documents. Details on how quickly NOAA charts, National Park Service materials, and other federal references will be updated have not been released.

With retaliatory tariffs set to hit next month and no new U.S.-Canada talks scheduled, the lake's new federal name looks likely to stay a symbolic flashpoint rather than the trade war's main event.