Abbreviate State Names: USPS vs AP Style

Yes, state names should be abbreviated in most formal and practical contexts, but the correct abbreviation depends on the style guide you are following. For mailing addresses, use the two-letter USPS abbreviations (e.g., CA, NY, TX). For general writing, AP style dictates using traditional abbreviations (e.g., Calif., N.Y., Tex.) in most cases, but there are important exceptions. This guide explains the two main systems, when to use each, and common mistakes to avoid.

Formula

This calculator is a lookup tool, not a mathematical formula. It takes a state name and a style choice and returns the correct abbreviation. The logic is:

• USPS style: Two uppercase letters, no periods (e.g., CA for California).
• AP style: Traditional abbreviations with periods, varying in length (e.g., Calif. for California, N.Y. for New York).

For a full list, consult the USPS or AP style guide. The calculator above demonstrates the concept with three common states.

Worked Example

Using the default values: State = California, Style = USPS.

1. Look up California in the USPS list: it is CA.
2. The result is CA.

If you select AP style, the result would be Calif.

Why Two Systems Exist

The United States Postal Service (USPS) introduced two-letter abbreviations in 1963 to accommodate the growing use of ZIP codes and automated mail sorting. These abbreviations are all-caps, no periods, and are designed for addresses on envelopes and packages. In contrast, the Associated Press (AP) style—used by journalists and many publishers—has its own set of traditional abbreviations that are more readable in prose. For example, “Calif.� is used in a sentence like “She moved to Calif. last year.� The two systems serve different purposes: USPS for mail, AP for text.

USPS Abbreviations: The Complete List

When writing a mailing address, always use the official USPS two-letter abbreviations. These are also used in most forms and databases. Here are the 50 states plus the District of Columbia:

• AL, AK, AZ, AR, CA, CO, CT, DE, FL, GA
• HI, ID, IL, IN, IA, KS, KY, LA, ME, MD
• MA, MI, MN, MS, MO, MT, NE, NV, NH, NJ
• NM, NY, NC, ND, OH, OK, OR, PA, RI, SC
• SD, TN, TX, UT, VT, VA, WA, WV, WI, WY
• DC for District of Columbia

Note that eight states are never abbreviated in USPS style: Alaska, Hawaii, Idaho, Iowa, Maine, Ohio, Texas, and Utah. Their names are always written in full on envelopes.

AP Style Abbreviations: When and How

In AP style, the rules are more nuanced. Here are the key guidelines:

• Abbreviate the names of all states that are not among the eight never-abbreviated ones when used in text (e.g., Calif., N.Y., Tex.).
• Do not abbreviate state names when they stand alone in text (e.g., “She lives in California.�).
• Always spell out the state name when it is part of a formal title or a mailing address.
• Use the traditional abbreviations, not the USPS two-letter codes, in prose.

For example: “The conference will be held in Austin, Texas, next month.� But: “The conference is in Austin, Tex.� when used in a dateline.

Common Mistakes and Misconceptions

One frequent error is using USPS abbreviations in formal writing. For instance, writing “I visited CA last summer� is incorrect in AP style; it should be “I visited California.� Another mistake is using periods with USPS codes (e.g., “C.A.�) or using the wrong abbreviation for states like Nebraska (NE, not NB) and Maryland (MD, not MA). Also, note that the USPS does not abbreviate Alaska, Hawaii, Idaho, Iowa, Maine, Ohio, Texas, or Utah—so “TX� is correct on envelopes, but “Tex.� is correct in AP prose.

How to Choose the Right Abbreviation

Your choice depends entirely on the context:

• Mailing addresses: Use USPS two-letter codes, no periods.
• Journalistic or general prose: Follow AP style, using traditional abbreviations only when the state name is paired with a city.
• Legal or academic documents: Often use the full state name, but check the specific style guide (e.g., Bluebook for legal, Chicago for academic).
• Data entry or forms: Use USPS codes for consistency and database compatibility.

If you are unsure, spell out the state name. It is rarely wrong.

Frequently Asked Questions

Should I use periods in state abbreviations?

It depends. USPS two-letter codes never use periods (e.g., CA). Traditional AP abbreviations do use periods (e.g., Calif.). In other contexts, such as legal citation, periods may or may not be used—check the relevant style guide.

What are the eight states that are never abbreviated?

Alaska, Hawaii, Idaho, Iowa, Maine, Ohio, Texas, and Utah. These are always written in full, both in USPS and AP style. This is because their traditional abbreviations are either too close to another state’s (e.g., ME vs. MD) or are not intuitive.

Is it “TX� or “Tex.� in a sentence?

In AP style, use “Tex.� when the state name follows a city (e.g., “Austin, Tex.�). In USPS style, use “TX� on envelopes. In general prose, spell out “Texas.�

Do I need to abbreviate state names in tables or charts?

Yes, in tables and charts, USPS abbreviations are standard because they are compact and unambiguous. For example, a column header might read “State (USPS)� and list CA, NY, etc.

What about U.S. territories?

USPS also provides two-letter codes for territories: PR (Puerto Rico), VI (U.S. Virgin Islands), GU (Guam), AS (American Samoa), and MP (Northern Mariana Islands). AP style typically spells out these names in prose.

Why is it “Washington, D.C.� and not “Washington, DC�?

In AP style, “D.C.� is used with periods when written in text. On envelopes, the USPS code is DC. The same rule applies to state abbreviations: periods in prose, no periods in addresses.

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in state | State name | - | California | 0
sel style | Style | USPS=1, AP=2
out abbr | Abbreviation | - | (style = 1) * (state = "California" ? "CA" : state = "New York" ? "NY" : state = "Texas" ? "TX" : "") + (style = 2) * (state = "California" ? "Calif." : state = "New York" ? "N.Y." : state = "Texas" ? "Tex." : "") | 0