The driest part of the Canadian prairies is often called the Palliser Triangle, after a 19th century explorer who first described a roughly triangular area that he felt to be poorly suited for farming.
In his final report to the British government Captain John Palliser suggested that a triangular portion of what is now the southern prairie provinces was a northern extension of the arid, central desert of the United States: “This central desert extends, however, but a short way into the British territory, forming a triangle, having for its base the 49th parallel from longitude 100° to 114° W, with its apex reaching to the 52nd parallel of latitude.” Palliser described this triangular area as “desert, or semi-desert in character, which can never be expected to become occupied by settlers.” To this day Palliser’s name is attached to the most arid region of the southern Canadian prairies.
The boundary of the Palliser Triangle is not fixed like a political boundary. Rather it fluctuates depending on climatic cycle, or the purpose of the person mentioning the region. Since Palliser’s original pronouncement, the area that people generally call the Palliser Triangle has shrunk. Today boundaries of physio-graphic regions such as the brown soil zone or the mixed grassland prairie ecoregion are often used to indicate the Palliser Triangle (see Figure PT-1).
Characterized by its aridity, the mixed grassland ecoregion has an annual water deficit (the amount that the potential evapotranspiration exceeds the precipitation) of 524 mm. It is a natural grassland with few native trees or wetlands. Its landscape is diverse, from level, glacial lake plains to the rolling Missouri Coteau. Climatic data for Leader, a town within this ecoregion, are typical of the area. In Leader the total annual precipitation is 352 mm and the annual snowfall is 101 cm. The mean July temperature is 18.9° C and the mean January temperature is -12.6° C.