On November 24, 1805, the decision of where to spend the winter was put to a vote — both York, an enslaved African, and Sacagawea, both a Native American and a woman, cast votes with the other men. This is significant, since it occurred many years before African Americans, Native Americans, or women were guaranteed the right to vote in elections. Lewis and Clark gave the thoughts of York and Sacagawea, at least in regards to the winter camp, equal weight with that of the white men of the expedition.

Ultimately, the group decided on an area near the Columbia River and the Pacific Ocean, in what is now Oregon, in which to build the camp they named Fort Clatsop. The winter they spent there was miserable: the weather was terrible, raining constantly and sometimes snowing; their bedding was infested with fleas; and everything they owned stayed musty and damp for most of the winter. They were unable to leave Fort Clatsop until March 23, 1806; there had been only 12 days without rain.

Despite these hardships, the expedition was able to establish trade with the nearby Clatsop Native Americans. Fort Clatsop also proved to be a site filled with interesting plants and animals, descriptions of which Lewis and Clark entered in their journals. A replica of the fort was built in 1955. It is now called the Fort Clatsop National Memorial, and can still be visited today.