Which event affected the development of jazz during the mid-to late 1900s?

The Civil Rights Movement significantly affected the development of jazz during the mid-to-late 1900s, as it provided a platform for African American musicians to express their struggles and aspirations through music. This era saw the emergence of genres like free jazz and avant-garde, reflecting the social changes and cultural upheaval of the time. Additionally, the popularity of jazz festivals and the rise of fusion jazz in the late 1960s introduced new audiences and styles, further shaping the genre's evolution.