Where Is Area Code 815?

Map of Illinois with area code 815 highlighted — Location of Area Code 815 and surrounding states.

Area code 815 is found in the US state of Illinois. Primarily servicing the city of Rockford (population: 187116), area code 815 covers 24 counties of Illinois.

Located in the Central time zone, area code 815 is on the same time as Chicago, IL.

Area code 815 was brought into effect on January 1, 1947.

Counties in Area Code 815

Boone,
Bureau,
Carroll,
DeKalb,
Ford,
Grundy,
Iroquois,
Jo Daviess,
Kane,
Kankakee,
Kendall,
La Salle,
Lee,
Livingston,
Marshall,
McHenry,
McLean,
Ogle,
Putnam,
Stephenson,
Whiteside,
Will,
Winnebago.

Most Populous Cities in Area Code 815

City	County	City Population	Time Zone
Rockford	Winnebago	187,116	CST
Plainfield	Will	95,378	CST
Crystal Lake	McHenry	59,550	CST
McHenry	McHenry	56,699	CST
DeKalb	DeKalb	46,071	CST
Romeoville	Will	40,098	CST
Lockport	Will	37,138	CST
Kankakee	Kankakee	37,023	CST
New Lenox	Will	34,312	CST
Belvidere	Boone	34,167	CST
Woodstock	McHenry	32,163	CST
Freeport	Stephenson	31,152	CST
Frankfort	Will	30,645	CST
Bourbonnais	Kankakee	29,002	CST
Ottawa	La Salle	24,043	CST
Loves Park	Winnebago	23,248	CST
Dixon	Lee	23,113	CST
Machesney Park	Winnebago	22,929	CST
Homer Glen	Will	22,909	CST
Sycamore	DeKalb	21,749	CST
Sterling	Whiteside	21,680	CST
Morris	Grundy	20,421	CST
Streator	La Salle	19,966	CST
Roscoe	Winnebago	19,835	CST
Rochelle	Ogle	14,676	CST