What ZIP codes does Illinois use for mail and package delivery?

Illinois (IL) operates within the 5-digit ZIP prefix range 600xx–629xx. Mail routed to state capital Springfield and key regional centers such as Chicago, Aurora, Naperville adheres to these official USPS boundaries.

Which telephone area codes are valid for Illinois?

Illinois is served by 15 active North American Numbering Plan (NANPA) area codes: 217, 224, 309, 312, 331, 447, 464, 618, 630, 708, 773, 779, 815, 847, 872. Synthetic telephone numbers for Illinois use those area codes with a 555 exchange, which is reserved for fictitious use.

How many counties are in Illinois?

Illinois is divided into 102 counties, including major administrative regions such as Cook, DuPage, Will, Lake. Generated street addresses use those names.

What postal formatting conventions and addressing quirks are unique to Illinois?

Chicago's zero-point Cartesian coordinate grid centered at State & Madison, where every 800 block number increments equal exactly one mile and require strict North/South and East/West directionals. Cook County's multi-layered property tax parcel alignments across 600xx–629xx postal delivery zones. All addresses generated on this platform format secondary unit designators (Apt, Ste, Fl) and street suffixes according to USPS CASS standards.

Are the Illinois addresses generated on this page real places?

No. All street numbers, recipient names, and telephone numbers generated for Illinois are entirely synthetic and randomized for software testing, database seed scripts, and form validation. They use Illinois ZIP codes from public USPS data and real city names, but they do not correspond to real individuals or private residences.

Random Illinois Address Generator

These addresses are randomly generated for software testing. They are not real people’s details: the street number, unit and recipient name are invented, and no record is checked for deliverability.

Randomly generated Illinois mailing addresses for software testing, form validation and staging data. Each record pairs a real Illinois city with a ZIP prefix that serves it and the county that city sits in, then adds a street number, a secondary unit designator and a recipient name that are invented.

Official Illinois Postal & Geographic Reference Specifications

Geographic & Postal Parameter	Official State Specification	Standardization Reference
Postal State Abbreviation	IL	USPS Publication 28 & ISO 3166-2:US
5-Digit ZIP Prefix Range	600xx–629xx	USPS prefix-to-state assignment
Administrative Jurisdictions	102 Total Counties	US Census Bureau regional boundaries
Active Area Codes (NANPA)	`217, 224, 309, 312, 331, 447, 464, 618, 630, 708, 773, 779, 815, 847, 872` (15 total)	North American Numbering Plan Administrator
State Capital	Springfield	US Census Bureau
Primary Time Zone	Central Time (America/Chicago, UTC-6 / UTC-5 DST)	IANA time zone database

Illinois Postal Geography & Key Cities

ZIP codes and Sectional Center Facilities are derived from public USPS ZIP code data, area codes from the North American Numbering Plan, and county names from US Census Bureau records. Street numbers and recipient names are synthetic, and nothing is checked against an address-verification service.

Cities the generator draws from:

Chicago
Aurora
Naperville
Joliet
Rockford
Springfield

Key Counties & Administrative Jurisdictions

County boundaries determine local sales tax jurisdictions in Illinois:

Cook County
DuPage County
Will County
Lake County
Kane County

Illinois Area Codes (IL)

Generated phone numbers use the area codes listed in the reference table above, paired with a 555 exchange so no number can reach a real line. Generate Illinois phone numbers.

Postal Delivery Standards & Format Nuances in Illinois

Chicago's zero-point Cartesian coordinate grid centered at State & Madison, where every 800 block number increments equal exactly one mile and require strict North/South and East/West directionals.
Cook County's multi-layered property tax parcel alignments across 600xx–629xx postal delivery zones.

Illinois Address Examples in USPS Publication 28 Format

Residential Delivery Point:
100 Main St, Apt 4B Chicago, IL 60601-1204

Commercial / Multi-Unit Delivery Point:
Illinois Logistics & Software Corp 500 Enterprise Way, Suite 300 Aurora, IL 60502-4810

Frequently Asked Questions about Illinois Addresses

What ZIP codes does Illinois use for mail and package delivery?: Illinois (IL) operates within the 5-digit ZIP prefix range 600xx–629xx. Mail routed to state capital Springfield and key regional centers such as Chicago, Aurora, Naperville adheres to these official USPS boundaries.
Which telephone area codes are valid for Illinois?: Illinois is served by 15 active North American Numbering Plan (NANPA) area codes: 217, 224, 309, 312, 331, 447, 464, 618, 630, 708, 773, 779, 815, 847, 872. Synthetic telephone numbers for Illinois use those area codes with a 555 exchange, which is reserved for fictitious use.
How many counties are in Illinois?: Illinois is divided into 102 counties, including major administrative regions such as Cook, DuPage, Will, Lake. Generated street addresses use those names.
What postal formatting conventions and addressing quirks are unique to Illinois?: Chicago's zero-point Cartesian coordinate grid centered at State & Madison, where every 800 block number increments equal exactly one mile and require strict North/South and East/West directionals. Cook County's multi-layered property tax parcel alignments across 600xx–629xx postal delivery zones. All addresses generated on this platform format secondary unit designators (Apt, Ste, Fl) and street suffixes according to USPS CASS standards.
Are the Illinois addresses generated on this page real places?: No. All street numbers, recipient names, and telephone numbers generated for Illinois are entirely synthetic and randomized for software testing, database seed scripts, and form validation. They use Illinois ZIP codes from public USPS data and real city names, but they do not correspond to real individuals or private residences.

Nearby & Bordering States

Explore test address generators for states sharing a geographic border with IL:

Illinois ZIP Prefixes

The first three digits of a ZIP code place an address within Illinois. These are the prefixes assigned to the state:

600xx, 604xx, 605xx, 606xx, 611xx, 627xx

Which processing facility sorts a given prefix is set by the current USPS labeling list L005 and changes as processing is consolidated, so it is not reproduced here. Look up a ZIP prefix to see its state and generate ZIP codes inside it.