MT is the official two-letter code for the American state of Montana. In the United States, every state has one of these short codes, always written with two capital letters and no full stops: CA for California, NY for New York, TX for Texas, MT for Montana. You use it in an address on an envelope, on a form, on a driving licence, or in a table where there is no room for the full name — 'Billings, MT 59101'. You do not use it when you are speaking. If you say the state out loud, you say 'Montana'. Nobody says 'I'm from em-tee'. It is also worth knowing that these two letters have other jobs in other places. In writing about machines or cars, mt can be short for 'manual transmission'; in older writing, Mt (with a small t and often a full stop, 'Mt.') is short for 'mount' in the name of a mountain — Mt. Fuji, Mt. Everest. That 'mount' one is where the letters first came from. But when you see MT next to a city name in an American address, it is Montana, every time. Montana itself is a big, thinly populated state in the northwest of the country, next to Canada — mountains, cattle, very few people.