On 27 August the US president signed an order renaming Lake Ontario “Lake America”, and said the change took effect at once. The order itself is less immediate: it gives the Interior Secretary thirty days to work with the Board on Geographic Names, update the federal register, and strike every reference to the old name from government maps, contracts and correspondence. The board’s own site says it discourages renaming anything without a compelling reason.

Nobody on the other side agreed. The Canadian prime minister pointed out that the name is more than four centuries old and predates both Confederation and the Declaration of Independence. The premier of Ontario said the lake would go on being Lake Ontario there. So did the governor of New York, whose state is the only one the lake touches. Canada keeps its own register of place names, and is not obliged to follow anyone else’s.

The name is not either country’s to begin with. It comes from a Wendat word read as the shining water, the great lake, the beautiful lake, and Europeans were writing it on charts by the middle of the seventeenth century — after failing to attach the names of their own officials and saints instead. The Grand Chief of the Wendat Nation called the order an attempt to erase his people’s history.

Then, on the Saturday, the maps came apart along the border. Google said its service would label the water Lake America for anyone looking from inside the United States, Lake Ontario for anyone looking from Canada, and both names at once for everybody else. MapQuest declined altogether: we are not changing it. There is no authority that can stop a country renaming things, and none that can make anyone else accept it.

The level is a ferry on that lake. Your cargo is written up in the name used by the shore you loaded it from, and the berths opposite do not all use it — a plate that disagrees turns you away and costs days you have not got. The second name can be bought at the dock before casting off, and that costs too. Same water, a name that depends on who is reading, and a bill either way.