Built in 1805 near present-day Astoria, Fort Clatsop was the winter quarters for the Corps of Volunteers for Northwest Discovery, more commonly known as the Corps of Discovery or the Lewis and Clark Expedition.

The Lewis and Clark Expedition wintered at Fort Clatsop before returning east to St. Louis in the spring of 1806. It took just over three weeks for the Expedition to build the fort, and it served as their camp from December 8, 1805 until their departure on March 23, 1806.

Fort Clatsop, the 1805-6 winter camp of the Lewis and Clark Expedition, was its home for more than 3-1/2 months. When the explorers first arrived at the estuary of the Columbia in November 1806, they followed its north bank. But their camps were exposed to ocean gales and hunting was poor.