Major Rivers of the U.S. Mountain & Basin Region

Rivers Shaping the Intermontane West

The Mountain and Basins (Intermontane Plateaus) region is defined by its internal drainage and iconic rivers:

1. Colorado River System

• Originates in the Colorado Rockies.
• Major tributaries: Green, San Juan, Gunnison, Little Colorado.
• Carves the Grand Canyon; lifeline for 40 million people.

2. Rio Grande

• Rises in Colorado’s San Juan Mountains.
• Forms US–Mexico border; empties into Gulf of Mexico.

3. Snake River

• Major Columbia River tributary.
• Flows through Idaho, Oregon, Washington; famed for Hells Canyon and Shoshone Falls.

4. Humboldt River

• Longest river entirely within Nevada.
• Ends in Humboldt Sink (endorheic).

5. Bonneville Basin Rivers

• Closed basin in western Utah: Bear, Weber, Ogden, Sevier Rivers.
• No ocean outlet; feed Great Salt Lake and wetlands.

6. Truckee River

• Lake Tahoe → Pyramid Lake (Nevada).
• Supports irrigation, hydropower, recreation.

These rivers have dictated settlement, agriculture, and water politics across the arid West.