Leonard Bernstein was a pioneer in the field of music. He was the first internationally acclaimed American-born orchestra conductor. Before Bernstein, all the great orchestras in Europe, as well as America, were led by someone from Europe or Asia. Bernstein traveled the world as a conductor and encouraged appreciation of the music of American composers, especially Aaron Copland. Bernstein not only composed classical works but also wrote music for Broadway, including West Side Story (1957) and On the Town (1944). For much of his life, he worked closely with the New York Philharmonic, with which he made several international tours and recordings.