|Native to||Illinois, Indiana, Kansas, Michigan, Ohio, Oklahoma|
|Revival||a small number of users in revival program|
Miami-Illinois (Myaamia [mjɑːmia]) is an indigenous Algonquian language formerly[clarification needed] spoken in the United States, primarily in Illinois, Missouri, Indiana, western Ohio and adjacent areas along the Mississippi River by the Miami and Wea as well as the tribes of the Illinois Confederation, including the Kaskaskia, Peoria, Tamaroa, and Mitchigamea.
Miami-Illinois is an Algonquian language within the larger Algic family. The name "Miami-Illinois" is a cover term for a cluster of highly similar dialects, the primary ones being Miami proper, Peoria, Wea, Piankeshaw, and, in the older Jesuit records, Illinois. About half of the surviving several hundred speakers were displaced in the 19th century from their territories, eventually settling in northeastern Oklahoma as the Miami and the Peoria. The remainder of the Miami stayed behind in northern Indiana.
The language was documented in written materials for over 200 years. Jacques Gravier, a Jesuit missionary who lived among the Kaskaskia tribe in the early 18th century, compiled an extensive and detailed Kaskaskia–French dictionary. Based on an analysis of its handwriting, it appears to have been transcribed by his assistant, Jacques Largillier.
Gravier's dictionary contains nearly 600 pages and 20,000 entries. It is the "most extensive of several manuscripts" which French missionaries made of the Illinois languages. The original document is held by Trinity College in Hartford, Connecticut. During the 18th and 19th centuries, the Illinois were subject to extermination by hostile tribes, as well as encroachment by European settlers. The French abandoned the Kaskaskia mission.
Eventually the surviving Illinois speakers went to the Indian Territory, later Oklahoma where the group became known as the Peoria. All of the Wea and Piankashaw were also forcibly relocated to Oklahoma, where they merged with the Peoria. About half the Miami proper remained in historic territory of present-day Indiana, the other half also being relocated to Oklahoma, eventually settling next to the Peoria. Because of the decline among the number of Miami-Illinois speakers, the language was not studied as extensively as many other Algonquian languages. It was not until 2002 that the manuscript was edited and published by Carl Masthay.
There is an extensive amount of data on the Miami-Illinois language. The problem with much of the data collected is that little of it was collected by trained phonologists and thus much of it is incomplete or incorrect. David Costa has written extensively on this language, compiling much of this data and correcting it in his book The Miami-Illinois Language.
The consonants of the Miami-Illinois language are typical to the "Central Algonquian" languages. It contains the voiceless stops and affricate p, t, k, tʃ; voiceless fricatives s, ʃ, h; nasals and liquids m, n, l; and the semivowels w, y. The linguist David Costa (2003) notes that "the original Proto-Algonquian consonants *p, *t, *k, * tʃ, *s, *ʃ, *h, *m, *n, *w, *j remain largely unchanged."
There is a small number of words in the Miami-Illinois language that have alternations between /s/ and /ʃ/ in their pronunciations. There are also opposite alternations where /ʃ/ occurs instead of /s/. Examples of both of these alternations seem to most prominently show themselves before the vowel /i/. Costa (2003) notes these "examples of words showing /ʃ/ for expected /s/ follow: /apeehʃia/, /teekweeʃita/, and /neehʃiaani/" 
Miami-Illinois has four short vowels, /i e a o/ and four long vowels, /iː eː aː oː/. Costa (2003) notes that "/a/ is a low non-front vowel however it can also be pronounced as a [ʌ] by some speakers. /o/ is a back round vowel ranging from [o] through [ʊ] to [u]. /e/ is a non-high front vowel ranging from [æ] through [ɛ] to [e]. Finally, /i/ is a high front vowel ranging from [ɪ] to [i]." These differences can occur from speaker to speaker and also from word to word.
The most important rule in the phonology of the vowels of the Miami-Illinois language is the iambic metrical rule, which is referred to by David Costa (2003) as the strong syllable rule (SSR). Syllables in this language are considered either strong or weak depending on whether they occur in an even or odd numbered spot within the word. Counting from left to right, the even numbered syllables are strong and the odd numbered syllables are weak. However, a long vowel is always considered strong and the syllable count is restarted from this point. Anytime a short vowel comes after a long vowel it will always be weak because the count will have started over and it will occur in an even-numbered syllable.
One important rule for the phonology of Miami-Illinois is called the "Vowel Devoicing Rule." In Miami-Illinois the weak vowels are devoiced any time they occur before a preaspirate. If a short vowel occurs before a preaspirate it will be devoiced if it follows a long vowel. This will also happen if it occurs in an odd-numbered syllable. However, if the vowel is in a strong syllable (or an even-numbered syllable) this rule does not apply. As Costa (2003) states it, "a vowel in an original second syllable can be devoiced only if a long vowel precedes it, thus rendering the vowel odd-numbered for the syllable count." 
Aside from the "Strong Syllable Rule" (Costa, 2003), there is separate system of accenting in the Miami-Illinois language. In this rule, the syllable count begins at the end of the word and goes backwards towards the start of it (unlike the Strong Syllable Rule, which begins at the beginning of the word and goes forwards). Vowels in both weak and strong syllable can be accented. It is most common for words in this language to take accents on their penultimate syllables, though if a weak syllable is subject to devoicing, it can not receive an accent. This shows that the devoicing rule comes before the accent rule.
Since the mid-1990s, the Miami Tribe of Oklahoma has embarked on a language revitalization program. Many Miami members have described the language as "sleeping" rather than "extinct" since it was not irretrievably lost.
The Myaamia Center is a joint venture between the tribe and Miami University. The Center's mission is..."to advance the research needs of the Miami Tribe of Oklahoma with a focus on myaamia language, culture and history."  It is directed by Daryl Baldwin, who taught himself Miami from historic documents and studies held by the Smithsonian's National Anthropological Archives, and has developed educational programs. Baldwin's children were raised as native speakers of Myaamia. Center staff develop language and culture resources using material that is often from translated missionary documents.
Some language and culture resources include
The revitalization effort is based on the work of linguist David Costa. Based on his extensive studies, he published The Miami-Illinois Language in 1994 as his Ph.D. dissertation and as a book in 2003. The book reconstructs the Miami-Illinois language and all its grammatical features. A related project at Miami University is one on ethnobotany, which "pairs Miami-language plant names with elders' descriptions of traditional plant-gathering techniques."