President Donald Trump signed an executive order directing U.S. federal agencies to refer to Lake Ontario as “Lake America.” The change applies to official U.S. government maps, documents, and the Geographic Names Information System. It does not rewrite international maps or force Canada to use the new name.
Trump announced the move in the Oval Office, saying the change was “official, effective immediately” and that the administration had filed the necessary paperwork. He described it as something he had been thinking about “for a long time.” The order follows the collapse of U.S and Canada trade talks last week and new 50% U.S. tariffs on about $20 billion of Canadian goods. Canada has said it will respond with matching counter-tariffs.
Lake Ontario is the smallest and easternmost of the five Great Lakes. It sits between Ontario, Canada, to the north and New York to the south. Roughly 52% of its surface area lies on the Canadian side of the 1909 boundary treaty line; the rest is in New York. The lake’s name comes from an Iroquoian/Huron word commonly translated as “lake of shining waters” or “beautiful lake.” That name has been in use on maps since the 1600s.
A single country can change the name it uses for a shared body of water in its own official records. It cannot compel the other country, shipping charts, or most private mapmakers to follow. Canadian Industry Minister Mélanie Joly said earlier this week, “We’ll always call it Lake Ontario.” Prime Minister Mark Carney’s office had not issued an immediate comment on the signed order.
The action follows a similar 2025 executive order that renamed the Gulf of Mexico the “Gulf of America” for U.S. federal use. Mexico rejected that change. Mapping companies later had to decide how to label the same water differently depending on the viewer’s location. Lake Ontario presents a similar problem because the international border runs through the water itself.
For now, U.S. federal agencies will use “Lake America.” Canadian agencies, most international bodies, and everyday speech on both sides of the border are expected to keep using Lake Ontario. The name on a shared lake does not move the border, change shipping rules, or alter water rights. It is a label change in one country’s official files.