The term "urban blues" is usually applied to post-World War II blues band music, but one of the forefathers of the genre in its pre-electric format was pianist Leroy Carr. Teamed with the exemplary guitarist Scrapper Blackwell in Indianapolis, Carr became one of the top blues stars of his day, composing and recording almost 200 sides during his short lifetime, including such classics as "How Long, How Long," "Prison Bound Blues," "When the Sun Goes Down," and "Blues Before Sunrise." His blues were expressive and evocative, recorded only with piano and guitar, yet as author Sam...