SOURCE: 4-1-09 (12-31-69)
The US has already lost more than a third of the indigenous languages that existed before European colonisation, and the remaining 192 are classed by Unesco as ranging between "unsafe" and "extinct".
As recently as 2008, the Alaskan tongue Eyak became officially extinct with the death of Marie Smith Jones, the last native speaker.
"We need more funding and more effort to return these languages to everyday use," says Fred Nahwooksy, of the National Museum of the American Indian.
Some 40 languages, mainly in California and Oklahoma, where thousands of Indians were forced to relocate as part of the notorious 19th Century Trail of Tears, have fewer than 10 native speakers.
The decline in American Indian languages has historical roots: in the mid-19th Century, the US government adopted a policy of Americanising Indian children by removing them from their homes and culture.
Within a few generations most had forgotten their native tongues.
But even so-called "dead" languages can be brought back to life.
The Wampanoag Indians of Massachusetts were the first to greet the pilgrims of the Mayflower - but until recently their language had not been spoken for a century.
In 1993, tribeswoman Jessie Little Doe Baird began researching and collecting word stems.
Now her daughter is the first native speaker in six generations and other children are learning.
Modern challenges to language survival remain.
There is a growing movement in the US to try to revitalise indigenous languages, but regaining the trust of community elders who were often punished for speaking their own language can be a problem.
Many now have to be persuaded to pass it on to a younger generation.
While the American media is often blamed for undermining other languages and cultures, the same technology might become the native languages' best chance for survival.
Native American filmmaking is a growing industry, providing a unique voice for communities that are often wary of being photographed or recorded in any form.