Many proposals to group these into higher-level families have been made, such as Joseph Greenberg's Amerind hypothesis. This scheme is rejected by nearly all specialists.
According to UNESCO, most of the indigenous American languages in North America are critically endangered, and many are already extinct. The most widely spoken indigenous language is Southern Quechua, with about 6 to 7 million speakers, primarily in South America.
Thousands of languages were spoken by various peoples in North and South America prior to their first contact with Europeans.[dubious– discuss] These encounters occurred between the beginning of the 11th century (with the Nordic settlement of Greenland and failed efforts in Newfoundland and Labrador) and the end of the 15th century (the voyages of Christopher Columbus). Several indigenous cultures of the Americas had also developed their own writing systems, the best known being the Maya script. The indigenous languages of the Americas had widely varying demographics, from the Quechuan languages, Aymara, Guarani, and Nahuatl, which had millions of active speakers, to many languages with only several hundred speakers. After pre-Columbian times, several indigenous creole languages developed in the Americas, based on European, indigenous and African languages.
The European colonizers and their successor states had widely varying attitudes towards Native American languages. In Brazil, friars learned and promoted the Tupi language. In many Latin American colonies, Spanish missionaries often learned local languages and culture in order to preach to the natives in their own tongue and relate the Christian message to their indigenous religions. In the British American colonies, John Eliot of the Massachusetts Bay Colonytranslated the Bible into the Massachusett language, also called Wampanoag, or Natick (1661–1663; he published the first Bible printed in North America, the Eliot Indian Bible.
The Europeans also suppressed use of indigenous American languages, establishing their own languages for official communications, destroying texts in other languages, and insisting that indigenous people learn European languages in schools. As a result, indigenous American languages suffered from cultural suppression and loss of speakers. By the 18th and 19th centuries, Spanish, English, Portuguese, French, and Dutch, brought to the Americas by European settlers and administrators, had become the official or national languages of modern nation-states of the Americas.
Many indigenous languages have become critically endangered, but others are vigorous and part of daily life for millions of people. Several indigenous languages have been given official status in the countries where they occur, such as Guaraní in Paraguay. In other cases official status is limited to certain regions where the languages are most spoken. Although sometimes enshrined in constitutions as official, the languages may be used infrequently in de facto official use. Examples are Quechua in Peru and Aymara in Bolivia, where in practice, Spanish is dominant in all formal contexts.
In North America and the Arctic region, Greenland in 2009 adopted Kalaallisut as its sole official language. In the United States, the Navajo language is the most spoken Native American language, with more than 200,000 speakers in the Southwestern United States. The US Marine Corps recruited Navajo men, who were established as code talkers during World War II, to transmit secret US military messages. Neither the Germans nor Japanese ever deciphered the Navajo code, which was a code using the Navajo language. Today, governments, universities, and indigenous peoples are continuing to work for the preservation and revitalization of indigenous American languages.
In American Indian Languages: The Historical Linguistics of Native America (1997), Lyle Campbell lists several hypotheses for the historical origins of Amerindian languages.
A single, one-language migration (not widely accepted)
A few linguistically distinct migrations (favored by Edward Sapir)
Multilingual migrations (single migration with multiple languages)
The influx of already diversified but related languages from the Old World
Extinction of Old World linguistic relatives (while the New World ones survived)
Migration along the Pacific coast instead of by the Bering Strait
Roger Blench (2008) has advocated the theory of multiple migrations along the Pacific coast of peoples from northeastern Asia, who already spoke diverse languages. These proliferated in the New World.
Language families and unclassified languages
The number of family members is indicated in parentheses (for example, Arauan (9) means the Arauan family consists of nine languages).
For convenience, the following list of language families is divided into three sections based on political boundaries of countries. These sections correspond roughly with the geographic regions (North, Central, and South America) but are not equivalent. This division cannot fully delineate indigenous culture areas.
There are approximately 296 spoken (or formerly spoken) indigenous languages north of Mexico, 269 of which are grouped into 29 families (the remaining 27 languages are either isolates or unclassified). The Na-Dené, Algic, and Uto-Aztecan families are the largest in terms of number of languages. Uto-Aztecan has the most speakers (1.95 million) if the languages in Mexico are considered (mostly due to 1.5 million speakers of Nahuatl); Na-Dené comes in second with approximately 200,000 speakers (nearly 180,000 of these are speakers of Navajo), and Algic in third with about 180,000 speakers (mainly Cree and Ojibwe). Na-Dené and Algic have the widest geographic distributions: Algic currently spans from northeastern Canada across much of the continent down to northeastern Mexico (due to later migrations of the Kickapoo) with two outliers in California (Yurok and Wiyot); Na-Dené spans from Alaska and western Canada through Washington, Oregon, and California to the U.S. Southwest and northern Mexico (with one outlier in the Plains). Several families consist of only 2 or 3 languages. Demonstrating genetic relationships has proved difficult due to the great linguistic diversity present in North America. Two large (super-) family proposals, Penutian and Hokan, look particularly promising. However, even after decades of research, a large number of families remain.
North America is notable for its linguistic diversity, especially in California. This area has 18 language families comprising 74 languages (compared to three families in Europe: Indo-European, Uralic and Turkic and one isolate: Basque). 
Another area of considerable diversity appears to have been the Southeastern United States; however, many of these languages became extinct from European contact and as a result they are, for the most part, absent from the historical record. This diversity has influenced the development of linguistic theories and practice in the US.
Due to the diversity of languages in North America, it is difficult to make generalizations for the region. Most North American languages have a relatively small number of vowels (i.e. four or five vowels). Languages of the western half of North America often have relatively large consonant inventories. The languages of the Pacific Northwest are notable for their complex phonotactics (for example, some languages have words that lack vowels entirely). The languages of the Plateau area have relatively rare pharyngeals and epiglottals (they are otherwise restricted to Afroasiatic languages and the languages of the Caucasus). Ejective consonants are also common in North America, although they are rare elsewhere (except, again, for the Caucasus region, parts of Africa, and the Mayan family).
In Central America the Mayan languages are among those used today. Mayan languages are spoken by at least 6 million indigenous Maya, primarily in Guatemala, Mexico, Belize and Honduras. In 1996, Guatemala formally recognized 21 Mayan languages by name, and Mexico recognizes eight more. The Mayan language family is one of the best documented and most studied in the Americas. Modern Mayan languages descend from Proto-Mayan, a language thought to have been spoken at least 5,000 years ago; it has been partially reconstructed using the comparative method.
Some of the greater families of South America: dark spots are language isolates or quasi-isolate, grey spots unclassified languages or languages with doubtful classification. (Note that Quechua, the family with most speakers, is not displayed.)
Although both North and Central America are very diverse areas, South America has a linguistic diversity rivalled by only a few other places in the world with approximately 350 languages still spoken and an estimated 1,500 languages at first European contact. The situation of language documentation and classification into genetic families is not as advanced as in North America (which is relatively well studied in many areas). Kaufman (1994: 46) gives the following appraisal:
Since the mid 1950s, the amount of published material on SA [South America] has been gradually growing, but even so, the number of researchers is far smaller than the growing number of linguistic communities whose speech should be documented. Given the current employment opportunities, it is not likely that the number of specialists in SA Indian languages will increase fast enough to document most of the surviving SA languages before they go out of use, as most of them unavoidably will. More work languishes in personal files than is published, but this is a standard problem.
It is fair to say that SA and New Guinea are linguistically the poorest documented parts of the world. However, in the early 1960s fairly systematic efforts were launched in Papua New Guinea, and that area – much smaller than SA, to be sure – is in general much better documented than any part of indigenous SA of comparable size.
As a result, many relationships between languages and language families have not been determined and some of those relationships that have been proposed are on somewhat shaky ground.
The list of language families, isolates, and unclassified languages below is a rather conservative one based on Campbell (1997). Many of the proposed (and often speculative) groupings of families can be seen in Campbell (1997), Gordon (2005), Kaufman (1990, 1994), Key (1979), Loukotka (1968), and in the Language stock proposals section below.
Hypothetical language-family proposals of American languages are often cited as uncontroversial in popular writing. However, many of these proposals have not been fully demonstrated, or even demonstrated at all. Some proposals are viewed by specialists in a favorable light, believing that genetic relationships are very likely to be established in the future (for example, the Penutian stock). Other proposals are more controversial with many linguists believing that some genetic relationships of a proposal may be demonstrated but much of it undemonstrated (for example, Hokan–Siouan, which, incidentally, Edward Sapir called his "wastepaper basket stock"). Still other proposals are almost unanimously rejected by specialists (for example, Amerind). Below is a (partial) list of some such proposals:
Good discussions of past proposals can be found in Campbell (1997) and Campbell & Mithun (1979).
Amerindian linguist Lyle Campbell also assigned different percentage values of probability and confidence for various proposals of macro-families and language relationships, depending on his views of the proposals' strengths. For example, the Germanic language family would receive probability and confidence percentage values of +100% and 100%, respectively. However, if Turkish and Quechua were compared, the probability value might be −95%, while the confidence value might be 95%.[clarification needed] 0% probability or confidence would mean complete uncertainty.
Several languages are only known by mention in historical documents or from only a few names or words. It cannot be determined that these languages actually existed or that the few recorded words are actually of known or unknown languages. Some may simply be from a historian's errors. Others are of known people with no linguistic record (sometimes due to lost records). A short list is below.
^Shapiro, Judith (1987). "From Tupã to the Land without Evil: The Christianization of Tupi-Guarani Cosmology". American Ethnologist. 1 (14): 126–139. doi:10.1525/ae.1987.14.1.02a00080.
^Campbell, Lyle (1997). American Indian languages: the historical linguistics of Native America. Ch. 3 The Origin of American Indian Languages, pp. 90–106. Oxford: Oxford University Press. ISBN 0-19-509427-1.
Boas, Franz. (1911). Handbook of American Indian languages (Vol. 1). Bureau of American Ethnology, Bulletin 40. Washington: Government Print Office (Smithsonian Institution, Bureau of American Ethnology).
Boas, Franz. (1922). Handbook of American Indian languages (Vol. 2). Bureau of American Ethnology, Bulletin 40. Washington: Government Print Office (Smithsonian Institution, Bureau of American Ethnology).
Boas, Franz. (1929). Classification of American Indian languages. Language, 5, 1–7.
Boas, Franz. (1933). Handbook of American Indian languages (Vol. 3). Native American legal materials collection, title 1227. Glückstadt: J.J. Augustin.
Bright, William. (1973). North American Indian language contact. In T. A. Sebeok (Ed.), Linguistics in North America (part 1, pp. 713–726). Current trends in linguistics (Vol. 10). The Hauge: Mouton.
Goddard, Ives (Ed.). (1996). Languages. Handbook of North American Indians (W. C. Sturtevant, General Ed.) (Vol. 17). Washington, D. C.: Smithsonian Institution. ISBN 0-16-048774-9.
Goddard, Ives. (1999). Native languages and language families of North America (rev. and enlarged ed. with additions and corrections). [Map]. Lincoln, Nebraska: University of Nebraska Press (Smithsonian Institution). (Updated version of the map in Goddard 1996). ISBN 0-8032-9271-6.
Goddard, Ives. (2005). The indigenous languages of the southeast. Anthropological Linguistics, 47 (1), 1–60.
Nater, Hank F. (1984). The Bella Coola Language. Mercury Series; Canadian Ethnology Service (No. 92). Ottawa: National Museums of Canada.
Powell, John W. (1891). Indian linguistic families of America north of Mexico. Seventh annual report, Bureau of American Ethnology (pp. 1–142). Washington, D.C.: Government Printing Office. (Reprinted in P. Holder (Ed.), 1966, Introduction to Handbook of American Indian languages by Franz Boas and Indian linguistic families of America, north of Mexico, by J. W. Powell, Lincoln: University of Nebraska).
Powell, John W. (1915). Linguistic families of American Indians north of Mexico by J. W. Powell, revised by members of the staff of the Bureau of American Ethnology. (Map). Bureau of American Ethnology miscellaneous publication (No. 11). Baltimore: Hoen.
Sebeok, Thomas A. (Ed.). (1973). Linguistics in North America (parts 1 & 2). Current trends in linguistics (Vol. 10). The Hauge: Mouton. (Reprinted as Sebeok 1976).
Sebeok, Thomas A. (Ed.). (1976). Native languages of the Americas. New York: Plenum.
Sherzer, Joel. (1973). Areal linguistics in North America. In T. A. Sebeok (Ed.), Linguistics in North America (part 2, pp. 749–795). Current trends in linguistics (Vol. 10). The Hauge: Mouton. (Reprinted in Sebeok 1976).
Sherzer, Joel. (1976). An areal-typological study of American Indian languages north of Mexico. Amsterdam: North-Holland.
Sletcher, Michael, 'North American Indians', in Will Kaufman and Heidi Macpherson, eds., Britain and the Americas: Culture, Politics, and History, (2 vols., Oxford, 2005).
Sturtevant, William C. (Ed.). (1978–present). Handbook of North American Indians (Vol. 1–20). Washington, D. C.: Smithsonian Institution. (Vols. 1–3, 16, 18–20 not yet published).
Vaas, Rüdiger: 'Die Sprachen der Ureinwohner'. In: Stoll, Günter, Vaas, Rüdiger: Spurensuche im Indianerland. Hirzel. Stuttgart 2001, chapter 7.
Voegelin, Carl F.; & Voegelin, Florence M. (1965). Classification of American Indian languages. Languages of the world, Native American fasc. 2, sec. 1.6). Anthropological Linguistics, 7 (7): 121-150.
Zepeda, Ofelia; Hill, Jane H. (1991). The condition of Native American Languages in the United States. In R. H. Robins & E. M. Uhlenbeck (Eds.), Endangered languages (pp. 135–155). Oxford: Berg.
Adelaar, Willem F. H.; & Muysken, Pieter C. (2004). The languages of the Andes. Cambridge language surveys. Cambridge University Press.
Fabre, Alain. (1998). "Manual de las lenguas indígenas sudamericanas, I-II". München: Lincom Europa.
Kaufman, Terrence. (1990). Language history in South America: What we know and how to know more. In D. L. Payne (Ed.), Amazonian linguistics: Studies in lowland South American languages (pp. 13–67). Austin: University of Texas Press. ISBN 0-292-70414-3.
Kaufman, Terrence. (1994). The native languages of South America. In C. Mosley & R. E. Asher (Eds.), Atlas of the world's languages (pp. 46–76). London: Routledge.
Key, Mary R. (1979). The grouping of South American languages. Tübingen: Gunter Narr Verlag.
Loukotka, Čestmír. (1968). Classification of South American Indian languages. Los Angeles: Latin American Studies Center, University of California.
Mason, J. Alden. (1950). The languages of South America. In J. Steward (Ed.), Handbook of South American Indians (Vol. 6, pp. 157–317). Smithsonian Institution Bureau of American Ethnology bulletin (No. 143). Washington, D.C.: Government Printing Office.
Migliazza, Ernest C.; & Campbell, Lyle. (1988). Panorama general de las lenguas indígenas en América. Historia general de América (Vol. 10). Caracas: Instituto Panamericano de Geografía e Historia.
Rodrigues, Aryon. (1986). Linguas brasileiras: Para o conhecimento das linguas indígenas. São Paulo: Edições Loyola.
Rowe, John H. (1954). Linguistics classification problems in South America. In M. B. Emeneau (Ed.), Papers from the symposium on American Indian linguistics (pp. 10–26). University of California publications in linguistics (Vol. 10). Berkeley: University of California Press.
Sapir, Edward. (1929). Central and North American languages. In The encyclopædia britannica: A new survey of universal knowledge (14 ed.) (Vol. 5, pp. 138–141). London: The Encyclopædia Britannica Company, Ltd.
Voegelin, Carl F.; & Voegelin, Florence M. (1977). Classification and index of the world's languages. Amsterdam: Elsevier. ISBN 0-444-00155-7.