The collar counties are the five counties of Illinois that border on Chicago's Cook County. After Cook County, they are also the next five most populous counties in the state. The collar counties (DuPage, Kane, Lake, McHenry, and Will) are tied to Chicago economically, but like many other suburban areas in the United States, they have very different political leanings from the core city. Chicago has long been a Democratic stronghold, but the collar counties are known for being historically Republican strongholds.