Winnebago County is a county in Illinois, United States, anchored by Rockford at the core of the Rockford metropolitan area near the Wisconsin state line. It had a population of 285,350 at the 2020 census, making it the state’s seventh most populous county after Cook County and its collar counties. The county covers 519 square miles (1,340 km2), of which 513 square miles are land and 5.9 square miles (15 km2) are water, centred near 42°20′N 89°10′W.
Rockford is the county seat, and its postal code is 61101. Winnebago County has 3 cities, 8 villages and 14 civil townships. The county sits in the Central time zone and carries FIPS code 17201.
Towns & Villages in Winnebago County
Rockford dominates the county’s population, with Loves Park and Machesney Park forming a continuous built-up area to its north along the Rock River. The remaining villages are smaller river and rail towns spread across the county’s farmland.
| Place | Type | Township | Pop. | ZIP |
|---|---|---|---|---|
| Rockford | City · seat | Rockford | 148,655 | 61101–61110, 61112, 61114 |
| Loves Park | City | — | 23,397 | 61111 |
| Machesney Park | Town | — | — | — |
| South Beloit | City | — | — | — |
| Cherry Valley | Town | Cherry Valley | 2,905 | — |
| Rockton | Town | Rockton | — | — |
| Roscoe | Town | Roscoe | — | — |
| Pecatonica | Town | Pecatonica | — | — |
| Durand | Town | Durand | 1,390 | — |
| New Milford | Town | — | — | — |
| Winnebago | Town | Winnebago | — | — |
Townships
Winnebago County is divided into 14 civil townships, which handle local roads and property assessment outside the incorporated places.
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Rockford | — | Rockford |
| Harlem | — | Northern Rockford suburbs |
| Owen | — | Rural, unincorporated |
| Cherry Valley | — | Cherry Valley |
| Seward | — | Rural, unincorporated |
| Rockton | — | Rockton |
| Roscoe | — | Roscoe |
| Shirland | — | South Beloit area |
| Harrison | — | Rural, unincorporated |
| Pecatonica | — | Pecatonica |
| Burritt | — | Rural, unincorporated |
| Durand | — | Durand |
| Winnebago | — | Winnebago |
| Laona | — | Rural, unincorporated |
ZIP Codes
- 61101–61110, 61112, 61114 — Rockford
- 61111 — Loves Park (also serves the northern Rockford edge)
Several smaller villages and unincorporated communities in the county share a Rockford-area ZIP rather than carrying a dedicated one of their own; these are omitted here rather than guessed.
Geography
Winnebago County lies in north-central Illinois on the Wisconsin border. The Rock River crosses the county from north to south through Rockton, Roscoe, and Rockford, joined by the Kishwaukee and Pecatonica Rivers, which drain the county’s farmland and low bluffs. The terrain is gently rolling prairie transitioning to river-valley woodland along the Rock.
The county borders Boone County to the east and Ogle County to the south. To the west lies Stephenson County. To the north, across the state line, is Rock County, Wisconsin, with Green County, Wisconsin, meeting the county’s northwest corner.
Demographics
Winnebago County had 285,350 residents at the 2020 census. Rockford (148,655) and Loves Park (23,397) are the county’s two largest communities, together holding roughly 60 percent of the county’s population. The county’s median household income runs below the Illinois state figure of $80,306 (2023 ACS); a current county-level figure was not available from the sources checked for this profile. Population density is about 556 people per square mile, concentrated in the Rockford-Loves Park-Machesney Park urban corridor along the Rock River, with the rest of the county remaining agricultural.
Economy & Local Life
Rockford is one of the largest centers of aerospace-parts manufacturing in Illinois, anchored by employers including Collins Aerospace and Woodward Inc. UPS operates a major air-cargo hub at Chicago Rockford International Airport, which has become one of the nation’s fastest-growing cargo airports. Healthcare is another major employer, with SwedishAmerican/UW Health, Mercy Health, and OSF Healthcare all operating hospital systems in the county, alongside Rockford Public School District 205. Outside the urban core, agriculture — corn and soybeans on the county’s prairie townships — remains the dominant land use.
History
Winnebago County was organized on January 16, 1836, from parts of Jo Daviess and LaSalle counties. It takes its name from the Ho-Chunk, historically known as the Winnebago, a Native American nation whose territory once extended into the region. Early settlers were predominantly New England transplants who arrived via the Galena-Chicago stage roads and later the railroads that made Rockford a manufacturing center. In the 1860 presidential election, the county voted heavily for Abraham Lincoln over Stephen Douglas.
Getting There
Interstate 39 and Interstate 90 cross the county, meeting near Rockford, along with U.S. Route 20 and U.S. Route 51. Chicago Rockford International Airport, just south of the city, offers commercial passenger and cargo service. Amtrak passenger rail does not currently serve the county; the former Chicago-Dubuque Black Hawk route through Rockford ended in 1981.
- Chicago, Illinois — about 90 miles east
- Madison, Wisconsin — about 70 miles north
- Freeport, Illinois — about 30 miles west
- Beloit, Wisconsin — about 15 miles north
Frequently Asked Questions
What is the Rockford postcode?
Central Rockford ZIP codes run from 61101 to 61110, with 61112 and 61114 covering other parts of the city.
Which city is the county seat?
Rockford is the county seat.
How many people live in Winnebago County?
The county had a population of 285,350 at the 2020 census.
How big is Winnebago County?
The county covers 519 square miles (1,340 km2), of which 513 square miles are land and 5.9 square miles are water.
What is the nearest commercial airport?
Chicago Rockford International Airport, located just south of Rockford, offers passenger and cargo flights.
Does Amtrak serve Winnebago County?
No. The former Chicago-Dubuque Black Hawk route through Rockford ended service in 1981.
Which counties border Winnebago County?
Boone and Ogle counties border it in Illinois, Stephenson County lies to the west, and Rock and Green counties in Wisconsin lie across the state line to the north.
More counties in this state: Towns and villages in Illinois.