NM is New Mexico. It is a US state, admitted on January 6, 1912, and it is not part of the country of Mexico. Its capital is Santa Fe and its largest city is Albuquerque.
Why the code is NM
Eight states begin with the letter N, more than any other initial except M. When the Post Office issued its two-letter list in October 1963, six of those eight had two-word names, and all six were solved by the same rule: keep the N, then take the first letter of the second word. North Carolina became NC, North Dakota ND, New Hampshire NH, New Jersey NJ, New York NY, and New Mexico NM.
So NM is not the first two letters of anything. It is N for New and M for Mexico, and the M is doing the entire job of separating the state from five siblings.
The two single-word N states had to be handled another way, and one of them shows how unsettled the list was at the start. Nevada took NV from the middle of its name. Nebraska was originally issued as NB in 1963 and reassigned to NE in 1969, because NB collided with New Brunswick in mail crossing the Canadian border. New Mexico's code has never changed.
Before 1963 the state had two competing printed forms. Newspapers following Associated Press style wrote N.M. Federal publications following the Government Printing Office wrote N. Mex. Both still turn up in archives, which is why the same state appears three ways depending on the decade of the document.
Codes people confuse with NM
| Code | State | Why the mix-up happens |
|---|---|---|
| NV | Nevada | Both are dry western states whose codes are N plus a consonant. People assume they are neighbors. They are not: Arizona sits between them. |
| MN | Minnesota | The same two characters in reverse order. One transposed keystroke sends a Santa Fe parcel to Saint Paul, and spellcheck cannot catch it. |
| NH | New Hampshire | Built by the identical rule, N plus the second word's initial. Anyone who has memorized the group has to recall which letter, not which state. |
| NJ | New Jersey | Another New-something code. In lists sorted alphabetically, NJ and NM land next to each other with only the second letter changing. |
| NY | New York | The best known of the New states, so it becomes the default guess when someone knows the code starts with N and stops thinking. |
Quick facts about New Mexico
- Capital: Santa Fe, established in 1610 and the oldest state capital in the country
- Largest city: Albuquerque
- Region: West, in the Southwest group
- Statehood: January 6, 1912, the 47th state. Arizona followed 39 days later, closing the contiguous 48
- Population band: 1 to 5 million
- Land area: 5th largest state, and landlocked
- Time zone: Mountain
Where you will see NM
Mail. New Mexico ZIP codes fall in the 87 and 88 blocks. Albuquerque runs in 871 and Santa Fe in 875. Any address in those ranges labeled MX has been misfiled as international.
License plates. New Mexico plates print the word USA beneath the state name. That is not decoration. It exists because drivers were being stopped and questioned about foreign registration. The red Zia sun symbol on the plate is the same emblem that appears on the state flag.
Print and media. New Mexico Magazine has run a reader column for decades collecting cases of businesses, ticket agents and government offices treating the state as a foreign country. Its title, One of Our Fifty Is Missing, is the state's own running commentary on the problem.
Sports. No NFL, NBA, MLB or NHL franchise plays in New Mexico, so the code almost never appears in a standings table. College coverage uses UNM for the University of New Mexico and NMSU for New Mexico State.
Technical search. Written in lower case, nm is the SI symbol for nanometer. Search results for the two letters mix state pages with semiconductor process nodes, which is an odd overlap given that Los Alamos and Sandia are both inside the state.
Learn the eight N codes
NC, ND, NE, NH, NJ, NM, NV, NY. Statedoku drills them as a set until the second letter stops being a guess.
Play the abbreviations quiz →