"[3] According to the United States Census Bureau, the East Cathlamet CDP has a total area of 1.71 square miles (4.4 km2), of which all of it is land and none of it is water.

As of the 2010 census,[6] there were 491 people, 227 households, and 149 families residing in the CDP.

The racial makeup of the CDP was 95.5% White, 0.2% African American, 1.8% Native American, 0.2% Asian, 0.0% Pacific Islander, 0.2% from other races, and 2.0% from two or more races.

29.1% of all households were made up of individuals, and 17.6% had someone living alone who was 65 years of age or older.

As of the 2000 census,[6] there were 491 people, 214 households, and 144 families residing in the CDP.

26.2% of all households were made up of individuals, and 13.6% had someone living alone who was 65 years of age or older.