Final answer:
Songwriters in the first half of the 20th century rarely performed their own songs, with the roles of composer and performer generally separated. This traditional division changed later in the century.
Step-by-step explanation:
In the first half of the 20th century, the norm was that songwriters rarely performed their own songs. The music industry often separated the roles between composers and performers. Composers focused on writing music and lyrics, while performers, who might be singers, actors in musical theatre, or musicians, would bring the compositions to life on stage, in recordings, or on the radio. This was a time when music and performance were heavily influenced by classical traditions and the notion of a 'pop star' as both songwriter and performer had not yet fully developed as it has in modern times.
Famous songwriters of the time, such as George and Ira Gershwin or Cole Porter, would often write for musical theatre, where performers would execute their works. Even with the emergence of more personal and politically charged songs from black musicians in genres like jazz and blues, the creators of these songs were not always the ones who made them famous. The role of the songwriter as a performer became more prominent with the popular culture and folk movements in the latter part of the 20th century, epitomized by artists like Bob Dylan and Leonard Cohen.