Geographic Regions and Area Codes

Area Code 707 is located in the northwestern part of California, covering a diverse range of counties and cities. The major counties include:

  • Sonoma
  • Solano
  • Napa
  • Humboldt
  • Mendocino
  • Lake
  • Del Norte
  • Trinity

The area code encompasses several significant cities such as Santa Rosa, Vallejo, Fairfield, Vacaville, Napa, and Petaluma. Due to the increasing demand for phone numbers, an overlay area code, 369, was introduced in February 2023.