The story
From the former Sumas Lake, which occupied the region until it was drained. From being a flatland prairie.
Etymology from Wiktionary, CC BY-SA 4.0.
Sumas Prairie
Today it means: A flatland in Fraser Lowland, North American Cordillera, North America, Americas, occupying the whole of Sumas district, British Columbia, Canada and part of Whatcom county, Washington, United States. Full definition →