Crosby was born in Los Angeles, California, and grew up in Humboldt and Sonoma counties in Northern California, raised by a single mother from an upper-class family who owned a record store in Fortuna, California. His great-grandfather was John C. Crosby, a congressman from Massachusetts and his ancestry on his mother's side is English and Native American. It is speculated that his father, who was a lounge guitarist whom he never met, may have been partially Japanese.
In 2003 he started his own record label, 2Blossoms Records & Media. Late 2007 and early 2008, Crosby released five download-only EPs, under the collective title Generica, which was to be "an exploration of people, places and American music." The first three volumes were solo acoustic guitar songs, while the last two were recorded along with VAST band members under the name "Jon Crosby and the Resonator Band". Crosby stressed the difference between this outfit and VAST:
When we put out "April" we were toying with the idea of releasing it as a JCRB album because the style was such a departure from previous VAST music. But then I thought, just because the music is different that doesn't mean it has to be a side project. Plus, a side project with the same members seemed a little bizarre. As we were recording the songs that would eventually go on Generica five we planned on putting them on a VAST album. Commercially it would have made more sense because people have heard of VAST but most people have not heard of JCRB. But to me, this music isn't VAST.