Collar counties
Collar counties is a colloquialism for DuPage, Kane, Lake, McHenry, and Will counties, the five counties of Illinois that border Cook County, which is home to Chicago. The collar counties are part of the Chicago metropolitan area and comprise many of the area's suburbs. While Lake County, Indiana, also borders Cook County, it is not typically included in the phrase "Collar Counties" due to different socioeconomic characteristics and positionality.
Collar Counties | |
|---|---|
Clockwise from top left: Rialto Square Theater (Joliet), Downtown Crystal Lake, Moser Tower (Naperville), Old DuPage County Courthouse (Wheaton), Great Lakes Naval Training Station (North Chicago) and Downtown Aurora. | |
| Country | United States |
| State | Illinois |
| Counties | DuPage, Kane, Lake, McHenry and Will. |
| Settled | 1770s |
| Named for | Their mutual proximity to and surrounding of Cook County. |
| Population (2012 Estimate) | |
| • Total | 3,143,257 |
| Time zone | UTC−06:00 (CST) |
| • Summer (DST) | UTC−05:00 (CDT) |
| Area code(s) | 224, 331, 630, 779, 815, 847 |
After Cook County, the collar counties are also the next five most populous counties in Illinois. According to the Encyclopedia of Chicago, there is no specifically known origin of the phrase, but it has been commonly used among policy makers, urban planners, and in the media.
In 1950, the Census Bureau defined the Chicago metropolitan statistical area as comprising Cook County, four of the five collar counties (excluding McHenry), and Lake County in Indiana. In 2010, reflecting urban growth, the Bureau redefined the area as comprising several additional counties in Illinois, Indiana, and Wisconsin.
As of 2019, there are 3,150,376 people residing in the collar counties, nearly 25% of the population of Illinois. Cook County and the collar counties combined are home to approximately 65% of Illinois's population.