On July 1, 1963, the Post Office Department introduced the five-digit ZIP Code. At the time, most addressing equipment could accommodate only 23 characters (including spaces) in the bottom line of the address. To make room for the ZIP Code, state names needed to be abbreviated. The Department provided an initial list of abbreviations in June 1963, but many had three or four letters, which was still too long. In October 1963, the Department settled on the current two-letter abbreviations. Since that time, only one change has been made: in 1969, at the request of the Canadian postal administration, the abbreviation for Nebraska, originally NB, was changed to NE, to avoid confusion with New Brunswick in Canada.
A list of state abbreviations since 1831 is provided below. A more complete list of current abbreviations, including all U.S. possessions, is available online at https://pe.usps.com/text/pub28/28apb.htm.
HISTORIAN
UNITED STATES POSTAL SERVICE
MAY 2019
Postal abbreviations for states/territories
| State/Territory | 1831 | 1874 | 1943 | June 1963 | Oct. 1963 - Present |
|---|---|---|---|---|---|
| Alabama | Al. | Ala. | Ala. | ALA | AL |
| Alaska | -- | Alaska | Alaska | ALSK | AK |
| Arizona | -- | Ariz. | Ariz. | ARIZ | AZ |
| Arkansas | Ar. T. | Ark. | Ark. | ARK | AR |
| California | -- | Cal. | Calif. | CALIF | CA |
| Colorado | -- | Colo. | Colo. | COL | CO |
| Connecticut | Ct. | Conn. | Conn. | CONN | CT |
| Delaware | De. | Del. | Del. | DEL | DE |
| District of Columbia | D. C. | D. C. | D. C. | DC | DC |
| Florida | Fl. T. | Fla. | Fla. | FLA | FL |
| Georgia | Ga. | Ga. | Ga. | GA | GA |
| Hawaii | - | -- | Hawaii | HAW | HI |
| Idaho | -- | Idaho | Idaho | IDA | ID |
| Illinois | Il. | Ill. | Ill. | ILL | IL |
| Indiana | Ia. | Ind. | Ind. | IND | IN |
| Iowa | -- | Iowa | Iowa | IOWA | IA |
| Kansas | -- | Kans. | Kans. | KANS | KS |
| Kentucky | Ky. | Ky. | Ky. | KY | KY |
| Louisiana | La. | La. | La. | LA | LA |
| Maine | Me. | Me. | Maine | ME | ME |
| Maryland | Md. | Md. | Md. | MD | MD |
| Massachusetts | Ms. | Mass. | Mass. | MASS | MA |
| Michigan | Mic. T. | Mich. | Mich. | MICH | MI |
| Minnesota | -- | Minn. | Minn. | MINN | MN |
| Mississippi | Mi. | Miss. | Miss. | MISS | MS |
| Missouri | Mo. | Mo. | Mo. | MO | MO |
| Montana | -- | Mont. | Mont. | MONT | MT |
| Nebraska | -- | Nebr. | Nebr. | NEB | NB* *to NE in 1969 |
| Nevada | -- | Nev. | Nev. | NEV | NV |
| New Hampshire | N. H. | N. H. | N. H. | NH | NH |
| New Jersey | N. J. | N. J. | N. J. | NJ | NJ |
| New Mexico | -- | N. Mex. | N. Mex. | NM | NM |
| New York | N. Y. | N. Y. | N. Y. | NY | NY |
| North Carolina | N. C. | N. C. | N. C. | NC | NC |
| North Dakota | -- | -- | N. Dak. | ND | ND |
| Ohio | O. | Ohio | Ohio | OHIO | OH |
| Oklahoma | -- | -- | Okla. | OKLA | OK |
| Oregon | -- | Oreg. | Oreg. | ORE | OR |
| Pennsylvania | Pa. | Pa. | Pa. | PA | PA |
| Puerto Rico | -- | -- | P. R. | PR | PR |
| Rhode Island | R. I. | R. I. | R. I. | RI | RI |
| South Carolina | S. C. | S. C. | S. C. | SC | SC |
| South Dakota | -- | -- | S. Dak. | SD | SD |
| Tennessee | Te. | Tenn. | Tenn. | TENN | TN |
| Texas | -- | Tex. | Tex. | TEX | TX |
| Utah | -- | Utah | Utah | UTAH | UT |
| Vermont | Vt. | Vt. | Vt. | VT | VT |
| Virginia | Va. | Va. | Va. | VA | VA |
| Washington | -- | Wash. | Wash. | WASH | WA |
| West Virginia | -- | W. Va. | W. Va. | W VA | WV |
| Wisconsin | -- | Wis. | Wis. | WIS | WI |
| Wyoming | -- | Wyo. | Wyo. | WYO | WY |
Sources: 1831, Table of Post Offices in the United States; 1874 and 1943, United States Official Postal Guide; June 1963, Postal Bulletin 20368; Oct. 1963, Post Office Department Publication 59, Abbreviations for Use with ZIP Code.
