Chicago ZIP Codes: The Full List, and the 28 That Aren't a Neighborhood at All

All 84 ZIP codes USPS assigns to Chicago -- and all of them sit in one county

USPS lists 84 ZIP codes with "Chicago, IL" as the primary place name. Every single one falls inside Cook County -- Chicago doesn't split across a county line the way Atlanta splits between Fulton and DeKalb, or the way several other major metros do. That's consistent with the finding on this site's Chicago county page: Cook County has been Chicago's home county since 1831, and the city has never grown past its edges.

Of the 84, 56 cover residential and mixed-use neighborhoods, clustered in the familiar 60601-60661 range. The other 28 are unique ZIP codes assigned to a single organization rather than a delivery area -- covered below.

28 of Chicago's ZIP codes aren't neighborhoods -- they belong to a single recipient

USPS occasionally assigns a ZIP code to one organization instead of a geographic area, when that organization's mail volume is high enough to justify routing it separately from the surrounding neighborhood. This site's Atlanta ZIP page covers one example -- the IRS's Atlanta service center holds a unique ZIP of its own. Chicago has 28 of them, nearly a third of its total, reflecting the city's role as a major aviation and banking hub.

O'Hare International Airport holds one: 60666 is a single PO Box zone -- 25 boxes serving roughly 112 airport businesses across the airfield, from cargo handlers like United Cargo and Korean Air Cargo to airline offices, customs, and other airport tenants -- rather than a code split by function. The ZIP right next to it in this list, 60668, isn't O'Hare's at all: it belongs to Commonwealth Edison, Chicago's electric utility, as a dedicated code for routing customer bill-payment mail -- a reminder that two ZIP codes sitting next to each other in a sequence don't necessarily share an owner. Downtown, several major banks have their own dedicated codes for high-volume mail processing. JPMorgan Chase's Chicago mail-processing center uses 60673 (and an associated code, 60670); the designation was added to postal records in October 2008, during Chase's expansion in the aftermath of the 2008 financial crisis. 60697 belongs to Bank of America, but the ZIP's history runs back further: it originally routed mail for Continental Illinois National Bank, which was the seventh-largest bank in the US when a 1984 run on deposits forced the FDIC to step in with a $7.5 billion rescue package -- the bailout that gave banking regulation the phrase "too big to fail" before the term became familiar again in 2008. BankAmerica acquired what remained of Continental Illinois a decade later, in 1994.

The remaining unverified codes in the list above -- 60664, 60669, 60674, 60675, 60677, 60678, 60680-60682, 60684-60691, 60693-60696, 60699, and 60701 -- follow the same pattern: USPS-assigned codes for single large-volume recipients or non-residential postal zones rather than delivery areas, though this site hasn't independently verified which specific organization holds each one.