The Great Basin is bordered by the Sierra Nevada mountain range to the west.

The Sierra Nevada mountain range forms the western boundary of the Great Basin, creating a dramatic contrast in geography. These mountains, which stretch from California into Nevada, are known for their rugged, snow-capped peaks, including Mount Whitney, the highest point in the contiguous U.S. The range plays a critical role in shaping the climate of the Great Basin by causing the rain shadow effect. This results in the Great Basin’s arid conditions, where precipitation is limited, and much of the region remains dry and desert-like. The Sierra Nevada's towering presence defines the western edge of the basin.