The Sierra Nevada is a major mountain range in the Western United States, running 640 kilometers primarily through California. It was formed about 4 million years ago through tectonic uplift and subsequent glacial erosion, which carved out spectacular features like Yosemite Valley. The range is home to Mount Whitney, the highest point in the contiguous United States at 4,421 meters, and General Sherman, the world's largest tree by volume, found in Sequoia National Park. The Sierra Nevada is vital to California's economy, as its snowpack acts as a natural reservoir, providing 60% of the state's water supply through a complex system of aqueducts. Historically, the range was the site of the 1848 California Gold Rush, which transformed the American West. Today, it faces threats from climate change, as shrinking snowpacks and increased wildfire frequency alter its delicate subalpine and alpine ecosystems.