For a long time, nearly everyone on Martha's Vineyard used a distinctive sign language. The island off the coast of Massachusetts used this unique form of communication from the middle of the 17th century to roughly the turn of the 20th. But by the mid-1960’s, signing on the island had ceased, since the last deaf person living there had died. Martha's Vineyard was just one of the places on the globe you could find "village sign language." Slowly, those places are disappearing. The Boston Globe explains why village sign is vanishing in an article
here.
