Mountain men
Because American's had little idea of what the lands west of the Mississippi river were like. The only small bits of information came from French trappers and traders and some Spanish and British explorers. Jefferson also funded the exposition to establish trade with the Native Americans and to find a waterway across the continent that spilled into the Pacific Ocean. He was also very fascinated about the geography and plant and animal life in the Western lands.
The first settlement in California was Sonoma. The people of Sonoma declared California as it's own country called the California Republic, with Sonoma as the Capital. It lasted June 14, 1846 until it's annexation to the U.S on July 9, 1846.
France gained help in trade through marriage of its traders to Native Americans.french
The fur traders faced hard portages and treacherous raids, and deadly insects that could cause suicide
If you mean enemies, the Blackfoot tribes (Blood, Blackfoot, Piegan and their allies the Atsina and Sarcee) fought almost continual war against the Crows, the Shoshone, the Cree, the Flatheads (Interior Salish) the Kutenai, the Assiniboin, the Pend d'Oreilles and against white explorers, trappers, mountain men and traders.
No. The Mormons are a religious group who settled in the Rocky Mountain area around the same time as the fur trappers.
On Sunday, March 22, 1778, Captain James Cook, in search of the Northwest Passage, reached Cape Flattery on the northwest tip of the Olympic Peninsula and established British claims to the region. Captain Cook’s stories of the abundance of sea otters start the first "fur rush" of trappers and traders to the Pacific Northwest.
Many of the early trappers/fur traders in America were French.
France
Trappers, traders, and emigrants on their way to California
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Indians
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Trappers, traders and Russian Orthodox missionaries.
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Fur traders and trappers from the American Fur Company.