The St Lawrence

Where it is

The St Lawrence drains the Great Lakes — about a fifth of the world's surface fresh water — into the Atlantic through a valley between the Canadian Shield to the north and the Appalachians to the south. It is a river, then a tidal estuary, then a gulf, and the transition is gradual: salt water reaches far inland and the estuary is wide enough at its mouth to be a sea. It is also a fault-bounded valley, and it produces earthquakes that surprise people who assume eastern North America is geologically quiet.

The land and water around it

• The estuary and gulfgulf

  The river widens into a tidal estuary and then a gulf open to the Atlantic. Its scale means fog, ice and strong tides, and its deep channel brings whales far upstream — belugas live in it year-round.

• The Lachine rapidsriver

  Rapids above Montréal that stopped ocean-going ships. The city is where it is because cargo had to be moved around them, which is how a portage becomes a metropolis.

• The Charlevoix craterbasin

  A large ancient impact structure on the north shore. It is now one of the most seismically active zones in eastern Canada — an old scar that stayed a weakness.

Its history, in short

This was the route into the continent. The Haudenosaunee and other Iroquoian-speaking peoples had towns along it before Jacques Cartier sailed up it in 1535, and the name Canada comes from a word for village he recorded there. French settlement followed the river — Québec at the narrows, Montréal at the rapids that stopped ships — and the fur trade ran up it and along the lakes beyond. Britain took the colony in 1763, and the river then carried the immigration that built industrial Canada, including the quarantine station at Grosse-Île that many did not survive. In the twentieth century the Seaway was cut to let ocean ships reach the lakes, flooding communities and rapids to do it.

Timeline

Dates are shown on a timeline rather than as changing shapes on the map. The globe draws modern boundaries only, and tinting a modern outline to stand for a historical one would state something we cannot source.

Places that carry meaning

• Old Québec17th century onward

  The only walled city north of Mexico, on the cliff above the narrows. Inscribed as World Heritage in 1985.

• Montréal1642 onward

  Founded above the rapids, and the head of ocean navigation before the Seaway. Its position made it the transfer point between river and interior for three centuries.

• The Saguenay fjordContinuous

  A deep glacial fjord joining the estuary from the north. Cold, deep water rises where it meets the river, concentrating food and drawing whales — which is why whale watching happens where it does.

Learn the language here

1. 1Understand which languages are spoken hereThe St Lawrence is multilingual. Start with which languages are used, by whom, and for what — the phrase list only covers one of them.Written by Globe Quest

Check yourself

• Why is Montréal where it is?

  Rapids stopped ocean ships there, so cargo had to be transferred

  A portage becomes a transfer point becomes a city. Québec, by contrast, is at the narrows.

• What did the Seaway bring besides cargo?

  Invasive species in ballast water, including zebra mussels

  The ecosystem change has not proved reversible — an infrastructure decision with a biological cost nobody priced.

Worth arguing about

• Six and a half thousand people were moved so ships could reach the lakes. How should a country account for that afterwards?
• A French-speaking society of eight million inside an English-speaking continent of four hundred million. What does it take to keep a language?

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