1. Why do the Prairie Provinces have granaries?

The Provinces does have granaries because its facilitates storage of wheat.

The region in Western Canada is called the Prairie Provinces and encompasses Manitoba, Saskatchewan, Alberta

This provinces constitute region with production of great wheat and also other natural resources such as petroleum, potash, natural gas etc

The term "Granaries" means a storehouse in a barn for threshed grain.

Therefore, the Prairie Provinces have granaries because it is used to store the wheat being harvested from Farm field.

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Prairie Provinces, the Canadian provinces of Manitoba, Saskatchewan, and Alberta, in the northern Great Plains region of North America.

Explanation: they constitute the great wheat-producing region of Canada and are a major source for petroleum, potash, and natural gas. With British Columbia they form the Western Provinces.