What Is the Abbreviation for Colorado?
The standard abbreviation for Colorado is CO. This page explains why Colorado uses CO, how the code fits into the modern USPS system, what older printed abbreviations looked like, and which nearby or similar state codes people commonly confuse with it.
What Is the Abbreviation for Colorado?
CO is the standard abbreviation for Colorado. Colo. still appears in older print sources, but CO is the standard code used in addresses, forms, databases, and current style guides.
Use CO for Colorado in mailing addresses, shipping labels, official forms, and database entries.
Why Colorado Uses CO
Colorado's USPS abbreviation is CO.
USPS has used CO for Colorado since 1963. The older form Colo. still appears in some older publications, but CO is the standard for modern addresses and forms.
Old Abbreviation for Colorado
Before the USPS two-letter system became the mailing standard in 1963, printed reference books and newspapers often used longer abbreviations with punctuation. For Colorado, that older style was usually Colo..
That older form still appears in historical texts, archival material, and some legacy style guides, but the modern postal and database standard is CO. If someone searches for old abbreviation for Colorado, the practical answer is to recognize Colo. and use CO in current writing and addresses.
How to Write Colorado in an Address
In standard American addressing, the state line uses the city name followed by the two-letter code and ZIP Code. The abbreviation stays uppercase and does not take periods.
That same format applies in checkout forms, school worksheets, CRM exports, spreadsheets, shipping labels, and government databases — anywhere a two-letter state code is required.
CO Compared With Similar State Codes
CO is sometimes checked against CA and CT, especially when several C-state abbreviations appear together.
Related Abbreviation Questions
These states share a first letter, region, or alphabetical position with Colorado and are commonly checked alongside it.
Capital, Region, and Context
Colorado belongs to the West region. Its capital is Denver, and its postal code CO is used in addresses, forms, and databases throughout the country.
Colorado entered the Union on August 1, 1876.
FAQ
What is the abbreviation for Colorado?
The standard USPS abbreviation for Colorado is CO.
What is the postal abbreviation for Colorado?
CO is the two-letter postal abbreviation for Colorado. It is the form used in mailing addresses, shipping labels, forms, and databases.
How do you abbreviate Colorado?
Abbreviate Colorado as CO in current USPS, mailing, and database use.
Why is Colorado abbreviated CO?
Colorado's USPS abbreviation is CO.
What does CO stand for?
CO stands for Colorado in the USPS state abbreviation system.
What is the old abbreviation for Colorado?
Older editorial styles often wrote Colorado as Colo.. For mailing and database use, the modern standard is CO.
How do you write a Colorado mailing address?
Use the city name, then the two-letter postal code CO, then the ZIP Code. For example: Denver, CO 00000.
What state is CO?
CO is the postal abbreviation for Colorado, located in the West region. The capital is Denver.
Test All 50 State Abbreviations
Now that you know CO stands for Colorado, see how many of the other 49 you can get right. The M-states and I-states trip up most people.