Are State Abbreviations Capitalized? | Uppercase Rule

You’ve seen both forms: “Austin, TX” on an envelope, and “Austin, Tex.” in older writing. That mismatch makes people pause and ask the same thing: are state abbreviations capitalized?

The short truth is that capitalization depends on which “abbreviation system” you’re using. Postal codes (the ones used on mail) are two letters in uppercase. Traditional text abbreviations (the ones used in prose) can be mixed case and may include periods.

Where You’re Writing	What To Use	Quick Model
Mailing label line	Two-letter USPS code in caps	Miami, FL 33101
School paper (general writing)	Spell the state out, or use your style guide’s text form	in Florida / in Fla.
City + state in running text	Pick one system and stay consistent	Albany, NY / Albany, N.Y.
Tables, charts, forms, data fields	USPS codes in caps are the cleanest default	State: WA
Bibliographies and citations	Follow the citation style (APA/MLA/Chicago)	Boston, MA
Legal or government writing	Use the standard named by the agency	Denver, CO
Informal notes and messages	Either spell it out or use USPS caps for speed	Landing in OR tonight
Headlines and slide titles	Spell out state names unless space is tight	Florida Storm Update

Are State Abbreviations Capitalized? In Mailing Lines And Writing

Yes in the postal system: the two-letter codes are uppercase by design. You’ll see AL, CA, NY, and the rest, with no periods.

In regular writing, you might still see older forms like “Calif.” or “Ala.” Those start with a capital letter, yet they aren’t all caps. They’re not “wrong”; they’re just a different set of abbreviations.

Postal Abbreviations Stay Uppercase

If you’re writing a mailing label, use the USPS two-letter codes. The official list lives in USPS two-letter state abbreviations, and it’s the one most forms and shipping systems expect.

The pattern is simple: City, space, state code, space, ZIP Code. When you stick to that format, mail sorting systems can read the line fast, cleanly.

• Correct: Portland, OR 97205
• Correct: San Juan, PR 00901
• Avoid: Portland, Or. 97205 (mixing systems)

Text Abbreviations Use Caps And Lowercase

Outside of mail labels, many style guides prefer either the full state name or a traditional abbreviation. Traditional abbreviations usually start with a capital letter and end with a period: “Ala.” “Ariz.” “Calif.”

Some older newspaper styles used forms like “N.Y.” with two periods. You’ll still run into them in archives, clippings, and older textbooks.

The main point: capitalization is not the problem. Both systems use capitals. The real difference is all caps (postal codes) versus capital + lowercase (text abbreviations).

Why Two Systems Exist

Postal abbreviations grew out of the need to fit the city, state, and ZIP Code on one short line. Two letters solved the space problem. Traditional abbreviations grew out of print conventions, where periods signaled shortened words.

Today, the USPS codes show up everywhere: shipping labels, online checkout forms, maps, and spreadsheets. Traditional forms still show up in prose when a style guide asks for them.

State Names Versus State Abbreviations

It helps to separate three choices that look alike on the page:

• State name (spelled out): California, New York, Texas
• USPS postal code: CA, NY, TX
• Traditional text abbreviation: Calif., N.Y., Tex.

Once you label the category, the capitalization question gets easier. Proper names (California) start with capitals. Postal codes are uppercase. Traditional abbreviations start with capitals and use lowercase letters as needed.

When “State” Is Lowercase

The word “state” is often just a common noun. In that role, it stays lowercase.

• She moved to the state last year.
• Each state sets its own rules.

When “State” Gets A Capital Letter

Capitalize “State” when it’s part of an official name or a formal label.

• State of New York
• State Department (as a proper name)
• State Route 1 (as a labeled route name)

Choosing The Right Form For Common Tasks

Most confusion comes from mixing systems in one document. Pick the form that matches the task, then use it the same way everywhere on the page.

Mailing Labels And Shipping Lines

Use USPS codes in caps. Don’t add periods. Don’t add extra letters. Keep the last line clean.

1. Write the city name as normal.
2. Add a space, then the two-letter state code in caps.
3. Add a space, then the ZIP Code.

If you’re filling out a form, the state field often expects the two-letter code. If you type “Calif.” into a state box, it can fail validation or trigger a drop-down mismatch.

School Papers And Essays

When space isn’t tight, spelling the state out is the safest move. It reads smoothly, and it avoids style conflicts across teachers and departments.

If you need an abbreviation, check the style your class uses. Many schools align with APA, MLA, or Chicago rules for locations. Those styles may prefer USPS codes in references while letting you spell out the state in the main text.

Resumes, Bios, And Short Profiles

Short blocks like resumes and speaker bios often use a city and state on one line. USPS codes in caps work well here because they save space and stay familiar.

• Seattle, WA
• Raleigh, NC
• Madison, WI

Tables, Spreadsheets, And Data Entry

Data loves consistency. Two-letter USPS codes are easy to sort, filter, and validate. They’re also the standard used by many public datasets.

If your table includes international locations too, add a separate column for country. Don’t try to squeeze country codes into the state field.

Citations, References, And Footnotes

In school and academic writing, location abbreviations can sneak into your work in a few places: publisher lines, database records, and figure captions. A simple rule keeps you out of trouble: spell the state out in sentences, then use the format your citation style expects in reference details.

If a reference list line already includes a city and state, postal codes in caps are widely understood and take up little space. Still, don’t guess. Check the style your instructor wants, then apply the same pattern across every reference entry.

• In running text: She studied in Massachusetts.
• In a short location tag: Boston, MA
• In a figure caption: Survey sites in OR and WA

One more detail that trips people: don’t add a period after a postal code at the end of a line. If the sentence needs a period, put it after the ZIP Code or after the closing parenthesis, not right after the two letters.

City, State, ZIP Punctuation That Reads Clean

Most readers expect one comma between the city and the state abbreviation. After that comma, a single space is enough. Then comes the two-letter code. On mail labels, the ZIP Code follows with a space.

When you add an apartment, suite, or building name, keep it on the line above. The last line stays focused on the postal pattern, which helps with scanning and data entry.

• Atlanta, GA 30303
• Helena, MT 59601
• Anchorage, AK 99501

If you’re using ZIP+4, keep the hyphen with the extra four digits. The state code still stays two letters in caps.

District Of Columbia And U.S. Territories

“State abbreviations” often gets used as shorthand for the whole set of USPS codes. That set includes DC and several territories. The same capitalization rule applies: two letters in caps.

DC can feel odd because people write it two ways: “Washington, DC” on mail, and “Washington, D.C.” in some prose. Treat those as two separate systems. Use DC (no periods) on a mailing label line. In a sentence, follow the style your publication uses, or spell out District of Columbia.

Territory codes work the same way as state codes. You’ll see PR for Puerto Rico and GU for Guam, both in caps. If you’re building a form or a spreadsheet, letting the same two-letter rule run across states and territories keeps sorting and filtering painless.

If a reader might not know a territory code, you can spell the place out on first use, then use the code in a tight list or table later on. That keeps the prose readable without breaking consistency in your data.

Government And Policy Writing

If you’re writing for an agency, match the style manual it follows. The U.S. Government Publishing Office style manual notes the Postal Service style for two-letter state abbreviations (see GPO Style Manual rule 9.13).

That rule lines up with what you already see on official forms: city, comma, space, two-letter state code, then ZIP Code.

Common Capitalization Traps

Most “wrong” state abbreviations aren’t about capitalization. They’re about mixing styles, adding punctuation that the system doesn’t want, or using a nonstandard short form.

Mixing Postal Codes With Periods

A postal code is two letters with no periods. “C.A.” and “N.Y.” aren’t USPS codes. They’re older text styles that look similar.

Using Lowercase Postal Codes

You might see “ca” in quick notes or in code. In published writing, it reads like a typo. Use “CA” unless you’re working inside a technical format that forces lowercase.

Abbreviating States That Are Already Short

Some state names are short enough that abbreviating them adds no value in prose. “Iowa” and “Utah” read cleanly as-is. On a mailing label, stick with IA and UT.

Clean Fixes You Can Apply Fast

When you edit a draft, scan for the same three items each time: commas, periods, and letter case. Fixing those three keeps your state abbreviations consistent.

What Shows Up	Use This Instead	Why It’s Cleaner
Los Angeles, Ca	Los Angeles, CA	USPS code is uppercase
Boston, M.A.	Boston, MA	Periods don’t belong in postal codes
Chicago IL 60601	Chicago, IL 60601	Comma improves readability
Portland, Ore 97205	Portland, OR 97205	Avoid mixing text and postal systems
Albany, New York	Albany, NY	Short line for mail and lists
Houston, TX.	Houston, TX	Extra period can look like an error
Miami, Fl, 33101	Miami, FL 33101	One comma is enough
DC (as D.C. in prose)	Washington, DC 20001	Mail labels use DC with no periods
“in TX” in a formal essay	in Texas	Spelling out reads smoother in prose

Quick Checklist For Consistent State Abbreviations

If you’re stuck, spell out the state name in sentences, then use USPS caps only in location lines today.

• If it’s a mailing label line, use the USPS two-letter code in caps.
• If it’s running text, spell the state out unless your style guide asks for an abbreviation.
• Don’t add periods to USPS codes.
• Don’t use lowercase postal codes in published writing.
• Pick one system per document, then stick to it.

So, are state abbreviations capitalized? Yes. The trick is using the right kind of abbreviation for the job, then keeping it consistent from the first line to the last.