The years 1870 to 1885 represent a period of transition in American popular song. Stephen Foster had died in 1864, though some of his songs continued to be republished. Tin Pan Alley would be a creation of the 1890s, though some of its leading songwriters, notably Gussie L. Davis, were practicing their craft by the mid-1880s.
In the period covered by this online collection American popular song saw the beginning of a shift from what one can call the Stephen Foster model, prevalent through the 1870s, to the Tin Pan Alley model, which becomes increasingly popular during the 1880s. Both models consist of verse and chorus (or "verse and refrain," to avoid the terminology problem of a "chorus" sung by a single singer), but the function of the two is different.
In the Stephen Foster song the chorus flowers from the verse but is not more important than the verse. Ask someone to sing "The Camptown Races" or "Jingle Bells" or "Father Come Home" and he or she will start with the verse: "The Camptown ladies sing this song . . . ," "Dashing through the snow . . . ," "Father, dear father, come home with me now. . . ." You may feel a shift of gears as the chorus comes: "Gwine to run all night . . . ," "Jingle bells, jingle bells . . . ," "Come home, come home . . . ," but the chorus does not seem more important than the verse. In most songs of this type, the chorus is, literally, a chorus: while the verse has been for solo voice and piano, at the start of the chorus three more voice-parts join in in harmony.
In the Tin Pan Alley song the verse sets up the chorus, which is the payoff. Often there is a major musical shift between verse and chorus: verse in narrative 4/4 time, chorus in swaying waltz rhythm. Even in songs with a strong narrative verse, such as "After the Ball" and "She Is More to Be Pitied Than Censured," the chorus alone is sung when someone is asked to sing the song informally. For some songs as well known as "A Bicycle Built for Two" and "The Band Played On" the verse is unknown save to specialists. As the division between verse and chorus became stronger, the change to a formal four-voice choral texture for the "chorus" became less and less prevalent. By the mid-1880s the newer model of popular song was definitely supplanting the Stephen Foster model, though the songs that have lasted from this period, such as "The Fountain in the Park" and "The Spanish Cavalier," tend to be ones with a familiar verse and chorus.