 On July 1, 1999, area code 971 was created as a concentrated overlay for most of the 503 territory, with the exceptions of Clatsop and Tillamook counties.Initially, 10-digit dialing was to become mandatory in that service area on January 30, 2000, but the date was extended until October 1, 2000.The previously exempted Clatsop and Tillamook counties were added to the 503/971 overlay on April 27, 2008.