“How Long Blues,” also known as “How Long, How Long Blues,” was first recorded by Leroy Carr with Scrapper Blackwell in 1928. It was claimed to have sold over one million copies, and became an early blues standard. Leroy Carr was the pianist and vocalist on the recording, and was accompanied by Blackwell on guitar. The song is notable for its “urban blues sophistication” as compared to the more common country blues of the era. Carr's vocal delivery and Blackwell's single note guitar soloing influenced a new generation of blues and jazz to follow.

The song is based on the 1925 Ida Cox song “How Long Daddy,” and in the blues tradition, Carr adapted the song to make it his own. The song was recorded in Indianapolis for Vocalion Records. It was Carr's and Blackwell's biggest hit, and they subsequently followed it up with “How Long Part 2”, “How Long Blues Part 3,” “New How Long Blues,” etc. to cash in on their hit. The song was inducted into the Blues Hall of Fame in 1988 as “Classic Blues Recording,” and into the Grammy Hall of Fame in 2012 for “Songs of Significant Historical Value.”