Final answer:
The Corps of Discovery spent 4 months at Fort Clatsop before starting their journey back to St. Louis. It took them about 7 months to return.
Step-by-step explanation:
The Corps of Discovery, led by Meriwether Lewis and William Clark, spent 4 months at Fort Clatsop in Oregon before starting their journey back to St. Louis in March 1806. It took them about 7 months to return to St. Louis, as they encountered challenges and delays along the way, including harsh weather and difficult terrain.
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