Sierra Nevada
Initial European-American exploration

American exploration of the mountain range started in 1827. Although prior to the 1820s there were Spanish missions, pueblos (towns), presidios (forts), and ranchos along the coast of California, no Spanish explorers visited the Sierra Nevada. The first Americans to visit the mountains were amongst a group led by fur trapper Jedediah Smith, crossing north of the Yosemite area in May 1827, at Ebbetts Pass.

In 1833, a subgroup of the Bonneville Expedition led by Joseph Reddeford Walker was sent westward to find an overland route to California. Eventually the party discovered a route along the Humboldt River across present-day Nevada, ascending the Sierra Nevada, starting near present-day Bridgeport and descending between the Tuolumne and Merced River drainage. The group may have been the first non-indigenous people to see Yosemite Valley. The Walker Party probably visited either the Tuolumne or Merced Groves of giant sequoia, becoming the first non-indigenous people to see the giant trees, but journals relating to the Walker party were destroyed in 1839, in a print shop fire in Philadelphia.

Starting in 1841, emigrants from the United States started to move to California via Sonora and Walker Passes.

In the winter of 1844, Lt. John C. Frémont, accompanied by Kit Carson, was the first European American to see Lake Tahoe. The Frémont party camped at 8,050 ft (2,450 m).
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