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.

Published: February 17, 2026Verified against NANPA and FCC records

Overlay Area Code

This area code shares its geographic footprint with an overlay code, so the same cities are served by two area codes. Because overlays leave existing numbers untouched, this region's relief planning favors adding codes over redrawing boundaries.

The codes serving this same region: area code 815 (Joliet).

In service since: 17-Mar-2007

Learn more about overlay and split area codes →

Demographics & Economics

Total Population: 1,156,724
Population Density: 71 people/sq mi
below U.S. average (U.S.: 95 people/sq mi)
Median Household Income: $67,385
below U.S. median (U.S.: $80,734)
Poverty Rate: 12.7%
near U.S. average (U.S.: 12.5%)
Unemployment Rate: 4.6%
below U.S. average (U.S.: 5.2%)
Education Attainment: Bachelor's Degree+
29.9%
below U.S. average (U.S.: 35.7%)
High School or Lower
33.1%

Statistics are population-weighted aggregations from Census ACS 5-year estimates. Population figures are approximate — see Sources & Methodology for details on how area code populations are derived.

See how this area code compares to all US area codes in the income ranking and density ranking.

Time Zone

Central Time (CT)

NANPA Relief Status

According to the latest NANPA analysis (July 2026), this area code is not currently listed as exhausting within the next 36 months. No relief planning is in progress for this NPA.

Source: NANPA NPA Relief Planning Reports · See all relief planning statuses

Current Time

Central Time (CT)

Prefix Utilization

Geographic Coverage

State

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

Area Code 779 geographic coverage map (light mode)

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 1,156,724. The population density is 71 people per square mile, which is lower than the national average of 95. The median household income is $67,385, which is lower than the national median of $80,734. Approximately 29.9% of adults hold a bachelor's degree or higher, compared to the national rate of 35.7%. This rate is lower than the national average. The poverty rate stands at 12.7%, which is near the national rate of 12.5%.

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%