Wahkiakum County // is a county located in the U.S. state of Washington. It is named after Chief Wahkiakum ("Tall Timber") of the Chinook. As of the 2010 census, the population was 3,978. The county seat is the town of Cathlamet, which is also the county's largest and only incorporated community. The County operates the Wahkiakum County Ferry, which connects Cathlamet to Westport, Oregon, across the Columbia River.
Wahkiakum County was formed out of Cowlitz County on April 25, 1854.