What huge crop did prairie farmers use to grow?

The huge crop that prairie farmers used to grow was wheat.

Wheat was (and still is) a major crop in the prairies due to:

* Climate: The prairie climate is well-suited for growing wheat, with hot summers and cool, dry winters.

* Soil: The prairie soil is rich and fertile, providing ideal conditions for wheat cultivation.

* Economics: Wheat is a valuable commodity, making it a profitable crop for farmers.

The prairies of North America, especially the Canadian prairies, have become known as the "breadbasket of the world" due to their vast wheat production.