On October 16, 1805, Lewis and Clark reached the confluence of the Snake and Columbia rivers. Here they received a friendly reception from the Yakamas and Wanapams. According to Clark, “we formed a camp at the point [and] after we had our camp fixed and fires made, a Chief came from their Camp which was about ¼ of a mile up the Columbia river at the head of about 200 men Singing and beeting on their drums Stick and keeping time to the musik, they formed a half circle around us and Sung for Some time, we gave them all Smoke, and Spoke to their Chiefs as well as we could by Signs informing them of our friendly disposition to all nations”. During their stay, the expedition purchased dozens of dogs to eat and received gifts of fish, horse meat, and fire kindling. The next day Clark and two other men explored the Columbia River ten miles upstream. He documented numerous settlements and vast quantities of salmon. On October 18, Lewis and Clark made celestial observations and took measurements of the Snake and Columbia rivers. They held a final council, and began their voyage down the Columbia.

The campsite at the point of the confluence is now within the boundaries of the 284-acre Sacajawea State Park. The day-use park affords a wide range of land and water-based recreational opportunities. It includes the Sacajawea Interpretive Center, which interprets the Lewis and Clark expedition and highlights the role played by Sacagawea. The park was established in 1927 and is now listed in the National Register as a sig­nificant example of the PWA Moderne architectural style.