Significant events for area code 503
| Date |
Details |
| 1947 | The original area code for Oregon |
| November 5, 1995 | Area code 503 was split with 541 covering all but the northwestern area of Oregon |
| July 1, 1999 | Area code 971 was overlaid on most of 503 |
| April 27, 2008 | Tillamook & Clatsop Counties were added to 971 |