What year did Aaron Copland become famous?

Aaron Copland rose to fame in the 1930s, particularly with the success of his ballet scores such as "Appalachian Spring" (1944) and "Billy the Kid" (1938). His distinctive style, which incorporated elements of American Folk Music, helped establish him as a leading figure in American Classical Music. By the end of the 1940s, he was widely recognized as one of the foremost composers in the United States.