Area codes 909 and 840 are telephone area codes in the North American Numbering Plan (NANP) for the far-eastern part of Los Angeles County and southwestern San Bernardino County in the U.S. state of California. Area code 909 was split from area code 714 on November 14, 1992. By August 1993, dialing of the area code became mandatory. Western Riverside County was split off from 909 into area code 951 on July 17, 2004. 909 still covers small portions of Corona, Riverside, Moreno Valley, and the entire city of Calimesa which are in Riverside County.