Lake Ontario was named by Indigenous people, not after the Canadian province of Ontario.
In late August 2026, U.S. President Donald Trump ordered that Lake Ontario, the easternmost of the Great Lakes, be renamed “Lake America” in government publications. Trump signed that executive order while he feuded with Canadian leaders over failed trade negotiations.
Some people on social media immediately claimed Trump wasn’t even targeting a Canadian name in his apparent attempt at retaliation. One X user wrote (archived) that Lake Ontario was named by Indigenous tribes hundreds of years ago, and Canada’s province of Ontario adopted the name later.
People made the same claim on Facebook (archived), Instagram (archived) and elsewhere on X (archived).
Preserved maps from early explorers show the name “Ontario” for the lake long before the province was labeled with the same name, which aligns with the lake’s and province’s histories as described by museums and historians. Therefore, we’ve rated this claim true.
According to the Canadian Encyclopedia, “Ontario” is thought to have come from an Iroquois word meaning “beautiful lake” or “sparkling water.” Ontario’s provincial government says the Iroquois word is “kanadario.”
Other sources transliterate the word differently. The National Museum of the Great Lakes, says “Ontario” derived from the Huron (also known as the Wendat, who spoke an Iroquois language) word “Ontarí’io,” meaning “great lake” or “beautiful water.”
Either way, “Ontario” was an indigenous word referring to a body of water, not a piece of land.
“Ontario” was first applied to the lake by Europeans in 1641, according to the Canadian Encyclopedia, and appears on maps of North America as early as 1656.
The lake’s name in the 1650 was in flux, at least for French cartographers exploring the area. Maps from 1653 and 1656 refer to the lake as, translated into English, Lake St. Louis or Lake Ontario. Notably, the 1656 map referred to the lake as Ontario first and Lake St. Louis second. Similarly, a map from 1657 called it Ontario Lake with a mention of the St. Louis name beneath it.
None of those maps labeled the land north of the lake, the present-day province of Ontario, as Ontario. In fact, this holds true even in a 1775 French map and a 1777 English map, both of which refer to the lake simply as “Lake Ontario.”
The province of Ontario came into being in 1867, according to the Canadian Encyclopedia, when Britain’s North American colonies joined together to become the Dominion of Canada. Before then, the land that’s now Ontario was known as Upper Canada and Canada West. Prior to 1791, it was part of a singular province of Quebec that included both today’s Ontario and Quebec.
While neither the Canadian Encyclopedia nor Canadian government webpages explicitly state that the province got its name from the lake, it at the very least used the name after the lake had long been called Ontario by the people around its shores.
For further reading, we previously investigated a claim that Trump demanded changes to Canada’s French-language rules as part of a trade deal.
