Area Code 773 History:
Area code 773 was put into service. Area code 773 was created from a split of area code 312. In 2009 area code 773 was overlaid with area code 872.
Counties in Illinois within area code 773 include:
Major cities or places in Illinois within area code 773 include:
Area codes 773 and 872 serve the areas outside of the Chicago downtown area. Chicago originally utilized area code 312 which was one of the original area codes assigned to Illinois in 1947. In 1996 area code 312 was split to form area code 773. Area code 312 then served the downtown area, or inside "The Loop" and area code 773 served the remainder of the city. On November 7, 2009 area code 872 was put into service. Area code 872 is an overlay of both 312 and 773.