Significant events for area code 909
| Date |
Details |
| November 14, 1992 | Area code 714 was split, with 909 covering the eastern area of the 714 area code. |
| July 17, 2004 | Area code was split, with 951 covering most of western Riverside County. |
| February 23, 2021 | Area code 909 was overlaid, with 840. |