Can a president really rename a lake?

US President Donald Trump has moved to rename Lake Ontario as “Lake America,” opening another flashpoint with Canada amid an ongoing trade dispute. Washington has recently imposed heavy tariffs on Canadian goods, further straining bilateral ties.

Trump says the name change reflects American identity and the nation’s connection to the Great Lakes. Critics, however, see it as a political gesture that could further strain relations with Canada.

Can Trump actually rename Lake Ontario? The answer is yes, but only within US jurisdiction. The federal government can alter the name used on official maps, documents, and records. However, Trump cannot compel Canada or other countries to adopt the new name.

Canada has already rejected the move. Prime Minister Mark Carney stressed that the lake has been known as Lake Ontario for more than 400 years. Ontario Premier Doug Ford also dismissed the proposal, declaring: “Lake Ontario. Now and Always.”

This is not Trump’s first attempt to alter a geographic name. He previously pushed to rename the Gulf of Mexico as the Gulf of America and to restore Mount McKinley as the official name of Denali.

Google Maps responded to the Gulf of Mexico dispute with a country-based naming system. Users in the US see “Gulf of America”, while users in Mexico see “Gulf of Mexico”. In many other countries, Google displays both names, side by side.

A similar approach could emerge if the US adopts “Lake America” while Canada continues to use “Lake Ontario”.

The issue is not entirely new. Japan refers to the body of water between Japan and Korea as the Sea of Japan, while South Korea calls it the East Sea. Google Maps reflects these local conventions, showing different names depending on the user’s location.

Supporters of Trump’s latest move could argue that renaming the lake reinforces American national identity. But critics warn of greater costs including further damage to US-Canada relations, confusion across maps and official documents, and concerns over historical identity.

The name Ontario itself has Indigenous roots dating back centuries -- long before the creation of modern Canada and the United States.

Ultimately, the dispute underscores a simple reality: geographical names are not just labels. They embody history, identity, and political power. Trump may be able to change what the US government calls the lake, but he cannot decide what the rest of the world calls it.

Trump may be able to change what the US government calls the lake. However, he cannot decide what the rest of the world calls it.