What kind of early 20th century music were Collins and Harlan known for?
Collins &amp; Harlan:  They sang ragtime standards as well as what were known as "Coon songs" – music sung by white performers in a black dialect. Coon song:  They were popular in the United States and the United Kingdom from around 1880 to 1920, though the earliest such songs date from minstrel shows as far back as 1848.
i don't know