Where is Area Code 815?
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 |
|---|---|---|
| Rockford | Winnebago | 187,116 |
| Plainfield | Will | 95,378 |
| Crystal Lake | McHenry | 59,550 |
| McHenry | McHenry | 56,699 |
| DeKalb | DeKalb | 46,071 |
| Romeoville | Will | 40,098 |
| Lockport | Will | 37,138 |
| Kankakee | Kankakee | 37,023 |
| New Lenox | Will | 34,312 |
| Belvidere | Boone | 34,167 |
| Woodstock | McHenry | 32,163 |
| Freeport | Stephenson | 31,152 |
| Frankfort | Will | 30,645 |
| Bourbonnais | Kankakee | 29,002 |
| Ottawa | La Salle | 24,043 |
| Loves Park | Winnebago | 23,248 |
| Dixon | Lee | 23,113 |
| Machesney Park | Winnebago | 22,929 |
| Homer Glen | Will | 22,909 |
| Sycamore | DeKalb | 21,749 |
| Sterling | Whiteside | 21,680 |
| Morris | Grundy | 20,421 |
| Streator | La Salle | 19,966 |
| Roscoe | Winnebago | 19,835 |
| Rochelle | Ogle | 14,676 |
Note: The above list is based off of the top 25 most populous cities in the area code as per 2012 United States Census Bureau estimates.
View all United States Area Codes.