If your paper can be argumentative, you could address topics such as:
Could the attack on Pearl Harbor have been permitted?
Did the United States have to go to war to abolish slavery?
Controversial topics such as the above are often interesting to research. In regards to music, why don't you choose a specific time period in American History when music was directly influenced by current events or vice versa. Consider the Jazz Age and how it reflects the attitude of the Post-World War I generation or protest music during the Vietnam War.