Lake America is the name the United States federal government now uses for Lake Ontario, the smallest and easternmost of the Great Lakes. President Trump signed an executive order on 27 August 2026 directing the Secretary of the Interior to make the change through the US Board on Geographic Names within 30 days. The order binds American federal agencies only. Canada, which shares the lake, has refused the name, and Lake Ontario remains the name in international use.
What the order actually directs
The document is titled "Honoring the American History of the Great Lakes and Renaming Lake Ontario as Lake America." It leans on stewardship figures rather than history alone: that the US Coast Guard operates nine of the eleven icebreaking vessels working the Great Lakes, and that the United States has spent close to $4 billion on Great Lakes ecosystem protection over the past decade.
The operative language identifies the feature as "the body of water currently named as Lake Ontario, bounded on the south and east by the State of New York, and on the north, west, and southwest by the Canadian province of Ontario." That phrasing is worth reading twice. It describes the entire lake, including the half that lies in Canadian waters, while simultaneously naming the Canadian province that forms three of its four shores.
Three instructions follow. The Interior Secretary, working with the Board on Geographic Names, has 30 days to make the change under federal naming law at 43 U.S.C. 364-364f. The Geographic Names Information System, the federal names database maintained by the US Geological Survey, must carry "Lake America" and drop references to "Lake Ontario." And federal agencies must update maps, contracts, documents and communications accordingly.
This is a narrower instrument than it sounds. GNIS is an American database of American federal usage. It has no authority over Canadian charts, Ontario road signs, the shipping documents of a Dutch-flagged freighter, or the atlas on your shelf.
How this differs from the Gulf renaming
The 2025 order that produced the Gulf of America was drafted with a deliberate offshore limit: it applied to the portion of the continental shelf bounded by Texas, Louisiana, Mississippi, Alabama and Florida, out to the maritime boundary with Mexico and Cuba. It renamed the American part and stopped.
The Lake Ontario order contains no such geographic carve-out. It names the whole lake. That difference is legally meaningless outside US federal usage, but it is the reason the Canadian response was sharper than Mexico's was in 2025. Prime Minister Mark Carney pointed out that the existing name is more than four centuries old, "pre-dating both the Confederation of Canada and the Declaration of Independence." Ontario Premier Doug Ford said it is "Lake Ontario to Canadians and the rest of the world. Now and forever."
The lake underneath the name
Lake Ontario is the runt of the Great Lakes by one measure and formidable by several others. Its surface covers about 19,000 square kilometres (7,340 square miles), the smallest of the five. But surface area is a poor proxy for water. Ontario holds roughly 1,640 cubic kilometres, more than three times the volume of Lake Erie, which spreads over a third more surface. Erie is a puddle by comparison: broad, shallow, quick to warm and quick to freeze.
The difference is depth. Ontario averages 86 metres (283 feet) and reaches 244 metres (802 feet) at its deepest. Because the surface sits at just 74 metres above sea level, the lake floor at that point lies about 170 metres below sea level. Only Superior and Michigan are deeper. That depth is also why Ontario almost never freezes over completely, even in a hard winter: there is too much stored heat in the water column for ice to win.
The lake stretches 311 kilometres (193 miles) west to east and about 85 kilometres (53 miles) across, with roughly 1,146 kilometres of shoreline once islands are counted. Around 5.6 million people live along its shores, split fairly evenly between the two countries, though the Canadian side is far denser: Toronto, Mississauga, Hamilton and St. Catharines sit on the north-west arc, while the American shore is a quieter run of Rochester, Oswego and Watertown.
Last in the chain, and the drop that gets you there
Ontario is the terminal lake. Water arriving in it has already passed through the other four, and its position at the bottom of the staircase explains two of the most consequential pieces of engineering in North America.
Lake Erie sits at 174 metres. Lake Ontario sits at 74 metres. Almost the entire 100-metre drop happens along the short Niagara River, most of it at Niagara Falls. That escarpment made the lower lake unreachable from the upper ones under sail, which is why the Welland Canal exists: 43.4 kilometres and eight locks that lift a ship the full 99.5 metres around the falls. The St. Lawrence Seaway, opened in 1959, completed the other half of the problem by making the lake reachable from the Atlantic. Water leaving Ontario flows out through the St. Lawrence River and reaches the ocean at the Gulf of St. Lawrence.
Ontari'io, and where the older name came from
The name being replaced is not English and not French. It comes from an Iroquoian word — usually given in Wendat as ontarí:io or oniatarí:io — meaning roughly "great lake" or "lake of shining waters." Carney cited the Wendat form directly in rejecting the change, glossing it as "the lake is beautiful, the lake is big."
The name reached European maps through French intermediaries in the seventeenth century, and it took a while to stick. French cartographers also tried Lac de St. Louis and Lac Frontenac before the Indigenous name won out. The lake gave its name to the province, not the other way round.
The Seneca Nation, whose historic territory reaches the lake's southern shore, issued a statement objecting that "the President cannot assert ownership over our culture or erase it through irresponsible political action." That is the recurring feature of American natural-feature renamings: the name being displaced is frequently the older one, and frequently Indigenous.
A boundary that runs down the middle
The international border crosses the lake along its long axis, with Canada holding slightly the larger share of surface and each country owning the lakebed on its own side. But the water is not divided in the way the seabed is. It is managed jointly, under the Boundary Waters Treaty of 1909, which created the International Joint Commission specifically so that the United States and Canada would have a standing body to settle disputes over shared water rather than litigating each one from scratch.
That treaty is why outflow at the Moses-Saunders Dam on the St. Lawrence is set by a binational board rather than by either government alone, and why shoreline flooding on Lake Ontario is a two-country argument. None of that machinery is affected by a naming order. The IJC's mandate is water levels, diversions and pollution, not toponymy.
What changed on maps, and what did not
Google Maps began showing "Lake America" to users in the United States on 30 August 2026. Its policy here is mechanical and was set during the Gulf episode: Google follows the official national names database of the country a user is in. So American users see Lake America, Canadian users see Lake Ontario, and users elsewhere see both, rendered as "Lake Ontario (Lake America)." That same split-label convention is what Google already applies to the Sea of Japan, which South Korea calls the East Sea.
What has not changed is everything outside American federal reach. Canadian federal and provincial mapping still reads Lake Ontario. The International Hydrographic Organization and the UN Group of Experts on Geographical Names are under no obligation to adopt an American designation, and neither has any mechanism to compel other states if it did. As the geographer Derek Alderman put it, there is no body that can stop the United States renaming the lake in its own records, and no body that can make anyone else follow.
In Congress, Representatives Debbie Dingell, Tim Kennedy and Joseph Morelle moved to introduce a bill titled the Hands Off Our Great Lakes Act to nullify the order. A parallel bill codifying Gulf of America passed the House in May 2025 and then stalled in the Senate, which is a reasonable guide to how these efforts tend to end.
Why this one arrived when it did
The order was not a cartographic project. Trump floated it on Truth Social on 25 August 2026, two days after US-Canada trade negotiations collapsed, and signed it on the 27th. The collapse triggered 50% American tariffs on roughly $20 billion of Canadian goods, with Canada announcing matching measures for 8 September. The lake was the message, not the subject.
That is worth separating from the geography, because the geography is durable and the naming is not. Lake Ontario will still be the smallest Great Lake by surface and the third deepest, still hold more water than Erie, still sit 100 metres below Erie's surface, and still drain a two-country basin to the Atlantic, whatever GNIS records. If you want the physical picture in more detail, our Lake Ontario geography guide covers the basin, and the complete guide to the Great Lakes puts all five in order.