The telephone area code 815 is most of the northern third of the state of Illinois, and also the core of the Chicago metropolitan area and the area around Moline. Considered to be one of the four original Illinois area codes set up in 1947. A new overlay area code, 779, was implemented on March 17, 2007. No old telephone numbers were reassigned to this area code; rather, it became available for new telephone prefixes on that date. A month earlier, on February 17, 11-digit dialing was implemented for area code 815 in preparation for the 779 overlay.

The towns, counties, cities, districts and the names of some of the important places which fall within this particular area code are as follows:

Adeline, Alden, Alworth, Amboy, Ancona, Apple river, Argo fay, Argyle, Arlington, Aroma park, Ashkum, Ashton, Avoca, Baileyville, Baker, Ballou, Beaverville, Beloit, Belvidere, Binghampton, ,Blackstone Blaine, Bonfield, Bonus, Bourbonnais, Braceville, Bradley, Braidwood, Brickton, Brookhaven, Brooks isle, Brookville, Buckingham, Bull valley, Bureau, Bureau junction, Byron, Cabery, Caledonia, Campus, Candlewick lake, Capron, Carbon hill, Cayuga, Cedar point, Cedarville, Center hill, Chadwick, Champlin, Chana, Channahon, Chatsworth, Chebanse, Chemung, Chenoa, Cherry, Cherry valley, Cissna park, Clare, Claytonville, Clifton, Clyde, Coal city, Coal hollow, Coleta, Compton, Coral, Cornell, Cortland, Council hill, Crescent city, Crest hill, Cresthill, Creston, Crystal lake, Cullom, Custer park, Daggetts, Dakota, Dalzell, Dana, Danforth, Danway, Davis, Davis jct, Davis junction, Daysville, Dayton, De pue, Deer grove, Dekalb, Depue, Depue junction, Derinda , Center, Diamond, Dimmick, Dixon,Donovan ,Dover, Durand, Dwight, Earlville, East Brooklyn, East Dubuque, East wenona, Egan, Eileen, Eldena, Eleroy, Elizabeth, Elwood, ,Emington, Eppards point, Esmond, Essex, Evans, Eylar, Fairbury, Fairdale, Farm ridge, Fay Flag center, Flagg, FlanaganFlorid, Forrest, Forreston, Frankfort, Franklin grove, Franklin grv, Freeport, Galena, Galt, Garden pr, Garden prairie, Gardner, Garfield, General foods coupon ctr, Genesee, Genoa, German valley, Gilman, Godley, Goodwine, Grand detour, Grand ridge, Grant park, Granville, Graymont, Hahnaman, Haldane, Hanover, Harding, Harmon, Harper, Harrison, Harvard, Hebron, Helmar, Hennepin, Herbert, Herscher, Hillcrest, Hinckley and HOLOMB.

There are lot of places where art and culture is practiced and that is why you will find real interest if you are a lover of art and culture. So, just go out there and enjoy every bit of the enriching local culture of this particular place.