Why Are There Two Different Abbreviations for the 50 States?
Dr. Richard Nordquist is professor emeritus of rhetoric and English at Georgia Southern University and the author of several university-level grammar and composition textbooks.
Updated on January 24, 2020There are three different ways to write state names: you can spell them out in their entirety, you can use traditional abbreviations, or you can use postal abbreviations. In most cases, postal abbreviations are appropriate and well understood. There are situations, however, in which it's correct to spell out state names. The decision will depend on the context of your writing and on the style guide you're following.
As a general rule, the names of states should be spelled out when they appear in sentences but abbreviated in other contexts. For example:
This rule applies also if you are writing something formal and following a style guide, such as the Chicago Manual of Style, MLA Style, American Psychological Association Publication Manual (APA), or Associated Press Style (AP).
In bibliographies, lists, charts where space is at a premium, reference lists, footnotes and endnotes, and in mailing addresses, state names are usually shortened using the postal abbreviation. This applies to Chicago Manual of Style and the American psychological Association Style (APA).
The two-letter, no-period state abbreviations recommended by the U.S. Postal Service (see "Postal Abbreviations" in the chart below) should always be used where a Zone Improvement Plan (ZIP) code follows. These postal abbreviations may also be used in any context where abbreviations are appropriate.
Some writers and editors still prefer to use the older forms of state abbreviations (see "Traditional Abbreviations in the table below), though this is rare. In 1987, the Secretary of Commerce switched to the more commonly used two-letter postal code abbreviations. If you follow the older practice, be consistent in your use of the traditional abbreviations, and remember that eight states (Alaska, Hawaii, Idaho, Iowa, Maine, Ohio, Texas, and Utah) are only rarely abbreviated when using the older (pre-ZIP code) forms.
Before 1963, there were no ZIP codes used on postal mail in the United States, and the U.S. Post Office preferred that people wrote out state and territory names completely to avoid confusion in sorting mail. In the early 1800s, it had established a standardized list of acceptable abbreviations, updating it in 1874. The list remained relatively unchanged until ZIP codes were introduced.
The addition of seven additional characters on a final address line (ZIP code plus two spaces) necessitated the shortening of state abbreviations to fewer characters. The Post Office aimed to fit the final address line into 23 characters to accommodate "major addressing systems."
Finally, United States may be abbreviated to U.S. when used as an adjective, but in formal writing, it's customarily spelled out as a noun. If you are following the Chicago Manual, you'll remove the periods to become US except in bibliography or reference entries pertaining to U.S. statutes, court cases, and other legal-context usages, which retain the periods. If you're following APA or AP, you will keep the periods there too. MLA prefers to spell out United States as an adjective or a noun in running text.
This handy chart has both the postal and the traditional abbreviations, for your reference:
STATE | POSTAL ABBREVIATION | TRADITIONAL ABBREVIATION |
Alabama | AL | Ala. |
Alaska | AK | Alaska |
Arizona | AZ | Ariz. |
Arkansas | AR | Ark. |
California | CA | Calif. |
Colorado | CO | Colo. |
Connecticut | CT | Conn. |
Delaware | DE | Del. |
District of Columbia | DC | D.C. |
Florida | FL | Fla. |
Georgia | GA | Ga. |
Hawaii | HI | Hawaii |
Idaho | ID | Idaho |
Illinois | IL | Ill. |
Indiana | IN | Ind. |
Iowa | IA | Iowa |
Kansas | KS | Kans. |
Kentucky | KY | Ky. |
Louisiana | LA | La. |
Maine | ME | Maine |
Maryland | MD | Md. |
Massachusetts | MA | Mass. |
Michigan | MI | Mich. |
Minnesota | MN | Minn. |
Mississippi | MS | Miss. |
Missouri | MO | Mo. |
Montana | MT | Mont. |
Nebraska | NE | Neb. or Nebr. |
Nevada | NV | Nev. |
New Hampshire | NH | N.H. |
New Jersey | NJ | N.J. |
New Mexico | NM | N.Mex. |
New York | NY | N.Y. |
North Carolina | NC | N.C. |
North Dakota | ND | N.Dak. |
Ohio | OH | Ohio |
Oklahoma | OK | Okla. |
Oregon | OR | Ore. or Oreg. |
Pennsylvania | PA | Pa. |
Rhode Island | RI | R.I. |
South Carolina | SC | S.C. |
South Dakota | SD | S.Dak. |
Tennessee | TN | Tenn. |
Texas | TX | Tex. or Texas |
Utah | UT | Utah |
Vermont | VT | Vt. |
Virginia | VA | Va. |
Washington | WA | Wash. |
West Virginia | WV | W.Va. |
Wisconsin | WI | Wis. or Wisc. |
Wyoming | WY | Wyo. |