Area Code 831 History:
Area code 831 was put into service. Area code 831 was created from a split of area code 408.
Counties in California within area code 831 include:
Monterey County, San Benito County, and Santa Cruz County.
Major cities or places in California within area code 831 include:
Area code 831 serves an area on the west coast of northern California which covers portions of Monterey County, San Benito County, and Santa Cruz County including the larger cities and communities of Hollister, Marina, Monterey, Salinas, Santa Cruz, Seaside, and Watsonville in addition to many smaller communities within the area code 831 service area.