Bloomfield recorded a few sessions for Columbia in 1964 that remained unreleased until after his death. In early 1965 he joined the Paul Butterfield Blues Band, which included Elvin Bishop and keyboardist Mark Naftalin, along with drummer Sam Lay and bassist Jerome Arnold, who had previously worked in Howlin' Wolf's band. Elektra Records producer Paul Rothchild recorded the band in spring 1965, but the majority of the tracks were not released until the 1990s. However, one of the tracks Rothchild recorded during his first pass at producing the group, a Nick Gravenites song titled "Born in Chicago," was included on the Elektra album "Folksong '65", which sold two hundred thousand copies when it was released in September 1965. "Born in Chicago" became an underground hit for the Butterfield Band. Their debut album, "The Paul Butterfield Blues Band", was recorded in September and released the following month.