Geographic Regions and Area Codes

Area Code 779 is located in the state of Illinois, covering a significant portion of northern Illinois. The major cities within this area code include Rockford, Joliet, and Plainfield. This area code spans across 23 counties, including:

  • Winnebago County
  • Will County
  • DeKalb County
  • McHenry County
  • Kankakee County
  • Boone County
  • Stephenson County
  • La Salle County
  • Lee County
  • Whiteside County
  • Grundy County
  • Livingston County
  • Ogle County
  • Bureau County
  • Iroquois County
  • Jo Daviess County

Area Code 779 is an overlay for Area Code 815, meaning both area codes serve the same geographic region. This overlay system was implemented to accommodate the growing demand for phone numbers in the region.