Area Code 779
Illinois
Area code 779 serves Illinois, primarily Joliet, in the Central Time (CT) time zone. It is an overlay area code sharing territory with area code 815.
Overlay Area Code
This area code is part of an overlay region, meaning the same geographic area is served by multiple area codes. Overlay codes were introduced to meet growing demand for phone numbers without requiring existing customers to change their numbers.
This area code shares its geographic region with: area code 815 (Joliet).
In service since: 17-Mar-2007
Geographic Coverage
Area code 779 serves Illinois, primarily the Joliet area, in the Central Time (CT). It covers 310 communities. The geographic center of this area code is approximately 41.67°N, 88.79°W.
History
Area code 779 serves as an overlay for the same territory as area code 815. It was introduced in 2007 to provide additional phone number capacity for the region. It shares its territory with area code area code 815.
Demographics
The estimated population served by area code 779 is approximately 2,598,680. The population density is 136 people per square mile, which is higher than the national average of 94. The median household income is $79,244, which is near the national median of $78,538. Approximately 28.7% of adults hold a bachelor's degree or higher, compared to the national rate of 35.0%. This rate is lower than the national average. The poverty rate stands at 10.2%, which is lower than the national rate of 12.4%.
Demographics & Economics
- Total Population
- 2,598,680
- Population Density
- 136 people/sq miabove U.S. average (U.S.: 94 people/sq mi)
- Median Household Income
- $79,244near U.S. median (U.S.: $78,538)
- Poverty Rate
- 10.2%below U.S. average (U.S.: 12.4%)
- Unemployment Rate
- 5.3%near U.S. average (U.S.: 5.2%)
- Education Attainment
- Bachelor's Degree+28.7%below U.S. average (U.S.: 35.0%)High School or Lower33.4%
Statistics are population-weighted aggregations from Census ACS 5-year estimates.See Sources for details.
Geographic Coverage
State
IL
Major Cities
- Joliet
- Rockford
- Bolingbrook
- Tinley Park
- Plainfield
- Romeoville
- DeKalb
- Crystal Lake
- Lake in the Hills
- McHenry
- New Lenox
- Woodstock
- Lockport
- Homer Glen
- Belvidere
- Kankakee
- Freeport
- Loves Park
- Machesney Park
- Frankfort
- Mokena
- Crest Hill
- Ottawa
- Sycamore
and 286 more cities
Time Zone
- Central Time (CT)
Current Time
County Coverage
Population-weighted county share based on aggregated ZCTA population (100% = total mapped population for area code 779).
| County | Population | Share |
|---|---|---|
| Will, IL | 507,783 | 19.5% |
| Winnebago, IL | 332,190 | 12.8% |
| McHenry, IL | 213,339 | 8.2% |
| Kendall, IL | 179,980 | 6.9% |
| Boone, IL | 179,923 | 6.9% |
| DeKalb, IL | 143,319 | 5.5% |
| Ogle, IL | 131,462 | 5.1% |
| LaSalle, IL | 126,131 | 4.9% |
| Kankakee, IL | 122,044 | 4.7% |
| Lee, IL | 104,497 | 4.0% |
| Grundy, IL | 91,546 | 3.5% |
| Lake, IL | 64,918 | 2.5% |
| Livingston, IL | 57,301 | 2.2% |
| Stephenson, IL | 54,507 | 2.1% |
| Whiteside, IL | 51,770 | 2.0% |
| Bureau, IL | 51,702 | 2.0% |
| Jo Daviess, IL | 34,957 | 1.3% |
| Cook, IL | 32,813 | 1.3% |
| Iroquois, IL | 31,768 | 1.2% |
| Carroll, IL | 30,763 | 1.2% |
| Kane, IL | 26,004 | 1.0% |
| McLean, IL | 7,401 | 0.3% |
| Putnam, IL | 6,268 | 0.2% |
| Henry, IL | 5,869 | 0.2% |
| Ford, IL | 5,801 | 0.2% |
| Marshall, IL | 4,624 | 0.2% |
Call Context
This area code serves the same geographic region as area code 815 in Illinois. It was introduced as an overlay of area code 815, meaning both codes serve the same geographic territory.
Nearby Area Codes
Area codes geographically closest to 779.
Other Area Codes in Illinois
Area codes that also serve Illinois, linked for easy comparison.
Frequently Asked Questions
Common questions about area code 779 and how phone numbering works.
Phone numbers are assigned based on where the number was originally provisioned, not the caller's current location. Mobile phones retain their number when users move, and businesses may use numbers from regions where they don't have a physical presence. VoIP services can also provision numbers from virtually any area code.
Yes, mobile phones can have numbers from any area code in the region they were activated. Wireless carriers assign numbers from available pools regardless of phone type. When users change carriers or move to new areas, they typically keep their original number, which may have a different area code than their current location.
Start by looking up the area code on this site to understand its general geographic region. For the specific number, options include using your carrier's caller ID features or checking public directories. If you suspect fraud, you can report it to the FTC. To file a complaint about robocalls or spoofed numbers, visit the FCC Consumer Complaint Center. You can also register your number with the National Do Not Call Registry to reduce unwanted calls. Keep in mind that caller ID can display any name the caller chooses to set.
When an area's pool of available phone numbers runs low, regulators may introduce an "overlay" area code that covers the same geographic territory as the original. Both codes coexist, and new numbers are assigned from whichever code has availability. This area code shares its region with area code 815, area code 815. Learn more in our overlay vs split guide.
While Arlington is a prominent city in this area code's coverage, the code serves the broader surrounding region as well. Area codes are assigned geographically and typically cover multiple cities, towns, and communities beyond any single anchor city.
The estimated total population served by area code 779 is based on aggregated U.S. Census Bureau data for the counties within this area code. The population varies significantly between dense urban codes serving millions and rural codes covering smaller populations. You can find the specific population figure in the demographics section above.