MI is Michigan. It is the official USPS two-letter code for Michigan, and no other state or territory shares it. Michigan's capital is Lansing, its largest city is Detroit.
Why the code is MI
ZIP codes went live on July 1, 1963. The last line of an address suddenly had to hold a city, a state and five digits inside a fixed run of character positions, and spelled-out state names would not fit. That October the Post Office Department issued Publication 59, which cut all fifty states to exactly two letters.
Michigan sat in the most crowded corner of that list. Four state names begin with the letters M and I: Michigan, Minnesota, Mississippi and Missouri. Only one of them could be MI, and Michigan is the one that got it. The other three were pushed onto whichever later letter separates them, which is how MinNesota produced MN, MiSsissippi produced MS and MissOuri produced MO. Michigan is therefore the odd one out in its own cluster: it is the only code of the four that reads as the plain first two letters of the state name.
Before 1963 the printed form was Mich. Federal documents, land deeds and newspaper datelines all used it, and crossword setters never gave it up.
Codes people confuse with MI
| Code | State | Why the mix-up happens |
|---|---|---|
| MN | Minnesota | The closest call of all. Both names start M-i, both states sit in the Upper Midwest, and both have a Lake Superior shoreline. Handwritten, the I and the N blur together. |
| MS | Mississippi | Also spelled M-i at the start, so anyone applying the first-two-letters rule reaches for MI. Mississippi is a Gulf Coast state, Michigan a Great Lakes one. |
| MO | Missouri | The fourth M-i name. Sports coverage widens the gap between the codes and the words, since Michigan shortens to MICH and Missouri to MIZZOU. |
| WI | Wisconsin | Neighbours across Lake Michigan, and the codes differ by a single opening letter while sharing the I. Address forms get these two swapped constantly. |
| MT | Montana | Eight codes begin with M, so people who remember only the initial guess by shape. MT is M plus one consonant, close enough to feel right in a hurry. |
Quick facts about Michigan
- Capital: Lansing
- Largest city: Detroit, so Michigan is one of the states where the capital is not the biggest city
- Region: Midwest, in the Rust Belt band
- Statehood: January 26, 1837, the 26th state
- Population band: over 10 million
- Land area: 11th largest state, split across the Upper and Lower peninsulas, both covered by the same MI code
- Time zone: Eastern for most of the state
Where you will see MI
Mail. Michigan ZIP codes occupy the 48 and 49 blocks. Detroit and the south-east corner run in 48, the west and north run into 49. A package addressed to a 48 ZIP with any code other than MI is a data-entry error.
License plates. Michigan plates print the state name in full and carry the Pure Michigan tourism slogan, so the two letters do not appear on the plate face. MI shows up on the registration paperwork and the insurance card instead.
Sports. The state's four major-league franchises all play in Detroit and all shorten to DET on a scoreboard. College desks use MICH for Michigan and MSU for Michigan State. Michigan is a rare case where the postal code is almost invisible in sports coverage.
Crosswords. Setters overwhelmingly want MICH rather than MI, because a four-letter answer is far easier to cross than a two-letter one.
International forms. MI is also the province code for Milano in Italy. Shipping systems that accept a bare two-letter region code without a country will happily read a Michigan address as a Lombardy one.
Drill the four M-and-I states
Statedoku puts MI, MN, MS and MO in the same grid, so you stop guessing and start knowing.
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