State Abbreviation Guide

What Is the Abbreviation for Illinois?

The standard 2-letter abbreviation for Illinois is IL.

State Abbreviation
IL
Traditional Form
Ill.
Capital
Springfield
Region
Midwest

Illinois Abbreviation

IL is the standard abbreviation for Illinois. Ill. still appears in older print sources, but IL is the standard code used in addresses, forms, databases, and current style guides.

2-letter postal code
IL
Traditional / AP style
Ill.
Address format
Springfield, IL
Takes periods?
No — write IL, not IL.

Illinois Abbreviation for Mailing and Forms

IL is the form used for Illinois in mailing addresses, shipping labels, official forms, and database records.

Mailing addresses
Shipping labels
Online checkout forms
Tax documents
Spreadsheets & databases
Government & school records

In all of these contexts write IL in uppercase. The form IL. with a period is incorrect for postal use.

AP Style and Traditional Illinois Abbreviation

Postal & forms IL Mailing addresses, shipping labels, online forms, and all data entry.
AP Style & editorial Ill. Newspapers, news releases, and most editorial style guides when a city name comes first.

What Does IL Stand For?

Illinois uses the USPS abbreviation IL.

USPS has used IL for Illinois since 1963. The older form Ill. still appears in older publications, but IL is the standard postal abbreviation today.

How to Write an Illinois Address

In a U.S. mailing address, write the city name, then IL in uppercase, then the five-digit ZIP Code. Never put a period after the abbreviation.

John Smith 123 Main St Springfield, IL ZIP

The same format applies in checkout forms, school worksheets, CRM systems, spreadsheets, shipping labels, and government databases — anywhere a two-letter state code is required.

Related Abbreviation Questions

These states share a first letter, region, or alphabetical position with Illinois and are commonly looked up alongside it.

What is the abbreviation for Idaho? Idaho's abbreviation is ID. What is the abbreviation for Indiana? Indiana's abbreviation is IN. What is the abbreviation for Iowa? Iowa's abbreviation is IA. What is the abbreviation for Hawaii? Hawaii's abbreviation is HI. What is the abbreviation for Kansas? Kansas's abbreviation is KS. What is the abbreviation for Michigan? Michigan's abbreviation is MI.

FAQ

What is the abbreviation for Illinois?

The standard USPS abbreviation for Illinois is IL.

What is the postal abbreviation for Illinois?

IL is the two-letter postal abbreviation for Illinois. It is the form used in mailing addresses, shipping labels, forms, and databases.

How do you abbreviate Illinois?

Abbreviate Illinois as IL in current USPS, mailing, and database use.

What is the two-letter abbreviation for Illinois?

IL is the official two-letter abbreviation for Illinois.

What is the Illinois state code?

IL is the two-letter state code used for Illinois in mailing addresses, forms, spreadsheets, and databases.

Why is Illinois abbreviated IL?

Illinois uses the USPS abbreviation IL.

What does IL stand for?

IL stands for Illinois in the USPS state abbreviation system.

What is the old abbreviation for Illinois?

Older editorial styles often wrote Illinois as Ill.. For mailing and database use, the modern standard is IL.

How do you write an Illinois mailing address?

Use the city name, then the two-letter postal code IL, then the ZIP Code. For example: Springfield, IL 00000.

What state is IL?

IL is the postal abbreviation for Illinois, located in the Midwest region. The capital is Springfield.