Missouri's postal abbreviation

Missouri’s two-letter USPS postal abbreviation is MO. Write it in uppercase without periods in a postal address. MO is different from the abbreviation for Mississippi, which is MS, and Montana, which is MT.

Meaning and context

The postal abbreviation identifies the state on an address line. It does not replace the city or ZIP Code. Use the recipient’s complete address, and verify an unfamiliar ZIP Code rather than trying to infer it from the state abbreviation.

Examples and usage

An illustrative last line might read Example City MO 12345, but an actual mailing must use a real city and matching ZIP Code. The example explains the position of MO rather than providing a usable delivery address.

What to check

In prose, a publication may prefer spelling out Missouri or use a different editorial convention. Follow the style appropriate to the document. A chat message containing mo can also mean something unrelated, so the postal interpretation depends on an address context.

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