Rathdrum Prairie

Kootenai County · dedicated 2025 · SH-53, milepost 0.45

The greatest floods in geological history once swept across the Rathdrum Prairie. Some 15,000 years ago, a lobe of the Cordilleran ice sheet crept south from Canada to Sandpoint. The ice formed a dam creating glacial Lake Missoula, containing as much water as Lakes Erie and Ontario combined. As the climate warmed, the dam failed multiple times, repeatedly emptying the lake. Torrents of water rushed through here. The Missoula Floods shaped much of the Northwest. Following those deluges, this lowland became a natural transportation corridor. People traveled along the valley at least 10,000 years ago. Today, highways run through it.

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David Rumsey Map Collection, Stanford Libraries

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Rathdrum Prairie

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