Sandburg also had an intense interest in folksongs. He began learning and collecting songs at 19 as he traveled west to the Kansas wheat fields in hopes of finding work. By the 1920s, he was in the habit of writing down songs on scraps of paper as he toured the lecture circuit; he also collected songs from friends, labor organizers, and folklorists (such as John Lomax). After the success of Abraham Lincoln: The Prairie Years in 1926, Sandburg decided to put together a collection of nearly 300 songs to be titled The American Songbag. The collection promoted the idea that the American folksong tradition was equal to its British counterpoint. The collection also proved unique for its time for including African-American folksongs. When published in 1927, the American Songbag, along with Sandburg's public performances of songs, helped to popularize the American folk music while also de-emphasizing the importance of the child ballad tradition.
Sandburg would continue to work on multiple projects, including the last four volumes of his Lincoln biography for which he would earn a Pulitzer Prize. He published Collected Poems in 1950, for which he won another Pulitzer Prize, and his autobiography, Always the Young Strangers, in 1953. He continued to lecture in the 1960s and sang, played guitar, and read from his works on a number of television programs. Sandburg died at his family's 245 acre farm, Connemara, in Flat Rock, NC, on July 22, 1967.