Area codes 503 and 971
Area code 503 originally covered the entire state of Oregon until November 5, 1995, when area code 541 began service. With that change, the northwest, and most heavily populated, corner of the state retained the 503 area code, while the rest of the state was assigned the new area code.
This was intended as a long-term solution. However, the Portland area is home to the great majority of Oregon's landlines, as well as most of its cell phones and pagers. Additionally, the Portland LATA extends for some distance into southwestern Washington, meaning several numbers in Washington's area code 360 weren't available for use. As a result, 503 was on the brink of exhaustion again within only three years.
On July 1, 1999, area code 971 was added to share the service area, 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.
Area codes 503 and 971 include communities in the following counties:
- Clackamas County
- Clatsop County
- Columbia County
- Linn County (far northern parts, including Scio, Lyons, and Mill City)
- Marion County (except southernmost parts around Jefferson)
- Multnomah County
- Polk County
- Tillamook County
- Washington County
- Yamhill County
- "Area Code History". Retrieved May 25, 2012.
- "Split of 503 (Oregon) Numbering Plan Area (NPA)" (PDF). North American Numbering Plan Administration. May 19, 1995. Retrieved May 25, 2012.
- "Concentrated Overlay of 503 Numbering Plan Area (NPA) with 971 NPA" (PDF). North American Numbering Plan Administration. July 21, 1999. Retrieved May 25, 2012.
- "Permissive Dialing Extended for the 503/971 Concentrated Overlay (Oregon)" (PDF). North American Numbering Plan Administration. December 10, 1999. Retrieved May 25, 2012.
- "Expansion of the Concentrated NPA 971 Overlay with NPA 503 (Oregon)" (PDF). North American Numbering Plan Administration. December 21, 2006. Retrieved May 25, 2012.
|Oregon area codes: 458/541, 503/971|
|West: Pacific Ocean||area codes 503/971||East: 458/541|
|Washington area codes: 206, 253, 360, 425, 509, 564|