What Is the Abbreviation for Missouri?
The standard abbreviation for Missouri is MO. This page explains why Missouri uses MO, 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 Missouri?
MO is the standard abbreviation for Missouri. Mo. still appears in older print sources, but MO is the standard code used in addresses, forms, databases, and current style guides.
Use MO for Missouri in mailing addresses, shipping labels, official forms, and database records.
Why Missouri Uses MO
Missouri's USPS abbreviation is MO.
MO became Missouri's standard postal abbreviation in 1963. The older form Mo. still appears in older writing, but MO is the form used in current addresses and forms.
Old Abbreviation for Missouri
Before the USPS two-letter system became the mailing standard in 1963, printed reference books and newspapers often used longer abbreviations with punctuation. For Missouri, that older style was usually Mo..
That older form still appears in historical texts, archival material, and some legacy style guides, but the modern postal and database standard is MO. If someone searches for old abbreviation for Missouri, the practical answer is to recognize Mo. and use MO in current writing and addresses.
How to Write Missouri 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.
MO Compared With Similar State Codes
MO is commonly checked against MI, MN, and MS because several M-state abbreviations can look similar in short lists.
Related Abbreviation Questions
These states share a first letter, region, or alphabetical position with Missouri and are commonly checked alongside it.
Capital, Region, and Context
Missouri belongs to the Midwest region. Its capital is Jefferson City, and its postal code MO is used in addresses, forms, and databases throughout the country.
Missouri entered the Union on August 10, 1821.
FAQ
What is the abbreviation for Missouri?
The standard USPS abbreviation for Missouri is MO.
What is the postal abbreviation for Missouri?
MO is the two-letter postal abbreviation for Missouri. It is the form used in mailing addresses, shipping labels, forms, and databases.
How do you abbreviate Missouri?
Abbreviate Missouri as MO in current USPS, mailing, and database use.
Why is Missouri abbreviated MO?
Missouri's USPS abbreviation is MO.
What does MO stand for?
MO stands for Missouri in the USPS state abbreviation system.
What is the old abbreviation for Missouri?
Older editorial styles often wrote Missouri as Mo.. For mailing and database use, the modern standard is MO.
How do you write a Missouri mailing address?
Use the city name, then the two-letter postal code MO, then the ZIP Code. For example: Jefferson City, MO 00000.
What state is MO?
MO is the postal abbreviation for Missouri, located in the Midwest region. The capital is Jefferson City.
Test All 50 State Abbreviations
Now that you know MO stands for Missouri, see how many of the other 49 you can get right. The M-states and I-states trip up most people.