Wahkiakum County, Washington (Wikipedia) Wahkiakum County (/wəˈkaɪ.əkʌm/) is a county located in the U.S. state of Washington. As of the 2020 census, the population was 4,422, making it one of the least populous counties in Washington. The county seat and only incorporated town is Cathlamet. The county was formed out of Cowlitz County in April 1854 and is named for Chief Wahkiakum (“Tall Timber”) of the Chinook, who is buried in the Pioneer Cemetery in Cathlamet. Washington State Fossil Sites and Collecting Localities (fossilspot.com)