Final answer:
Singing schools were the main vehicle for disseminating shape-note music.
Step-by-step explanation:
The main vehicle for disseminating shape-note music was singing schools. Singing schools played a significant role in the spread of shape-note music during the 18th and 19th centuries. These schools provided musical education and training to individuals, teaching them to read and sing shape-note music, which is a form of musical notation that uses specific shapes to represent different pitch levels.