[6] In the 18th and early 19th centuries, the Clatsop occupied an area on the south bank of the Columbia River stretching from Point Adams to Youngs Bay.

To the south, past Tillamook Head, was the territory of the Nehalem, a Salishan-speaking group to which the Clatsop have strong ties.

[10] The expedition named their last encampment Fort Clatsop after the tribe, whose nearest major village was approximately 7 miles (11 km) away.

According to the journals of William Clark, the Clatsop comprised about 200 people living in three separate villages, with large longhouses constructed of cedar planks.

The Clatsop and Chinook asked for higher prices from the American expedition for their goods at a time when the Corps' supply of "Indian gifts" had dwindled.

[10] From the 1830s-1850s, Clatsop society began experiencing a rapid decline after smallpox, measles, malaria, and other diseases ravaged the Columbia River.

[clarification needed] Individual families affiliated with one another in small villages and seasonal camps located near food sources.

[7] Most Clatsops spoke Chinook Jargon by the time Lewis and Clark's Corps of Discovery made contact with them.

[citation needed] The Chinook Indian Nation is an unregocnized group which claims descent from the Clatsop people.

In January 2001, the Chinook Indian Nation gained official federal recognition through an executive order by President Bill Clinton.

[citation needed] The Clatsop-Nehalem Confederated Tribes are an unrecognized group who claim descent from the Clatsop people.

[7][9] This is the first land owned by the Clatsop-Nehalem Confederated Tribes since they were displaced by European Americans beginning nearly 200 years ago.