| About 300 years ago fur traders |
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| In the past century the water quality |
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| Sailing is a popular sport in the region |
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| Cargo ships bring raw materials from the Great Lakes |
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| When the Ice Age ended, the basin of the Great Lakes region |
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| Water levels of the lakes have gone down |
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| The Great Lakes are situated |
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| The St Lawrence Seaway makes it possible |
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| Niagara Falls is located |
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| Because the lakes are at different sea levels |
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