. "-8" . "Clayton is an unincorporated community in Stevens County, Washington, United States. It is located along U.S. Route 395 4.5 miles (7.2 km) northwest of Deer Park, and has a post office with ZIP code 99110.Clayton was founded in 1889 and was named for nearby clay deposits.The Washington Brick Company was established in 1893."@en . "-7" . "509" . . "687.019"^^ . . . . "Clayton, Washington"@en . "99110" .