A vertical line to left of multiple staves indicate to a musician to play music on all staves at the same time.
Answer:
From a musical point of view, this migration brought Gospel and blues music to a wider audience, and northern and western cities became a place for African American musical innovation. The search for a better life also led to changes in the way performers chose to present themselves. For example, singer Noble Sissle refused to perform in black face, which, at the time, was still common for African Americans. Marian Anderson, whose grandfather had migrated to Philadelphia shortly after emancipation, studied opera and, when she performed traditional spirituals, she did so in a trained vocal style. Composer Spencer Williams is an example of an African American who migrated from New Orleans to perform and live in Chicago and later New York during the Great Migration. Listen to his song, "I Ain't Got Nobody" performed by Hattie Ellis. Another wave of African Americans to the north and west occurred after World War II. An example is blues great Honeyboy Edwards, who left the Missisippi Delta to live and perform in Chicago in 1950. Listen to him sing "Sweet Home Chicago," a song believed to have been written by Robert Johnson.
Explanation:
https://library.ric.edu/c.php?g=907570&p=6549202
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