The Nashville number system is a notational practice used by commercial musicians to represent the functional harmony of a complete song on a single sheet of paper. As a result, it can be considered an alternative format to the standard system of Roman numerals and figured bass commonly used in North American music theory classrooms. This article explains the mechanics of the Nashville number system, highlighting its differences with Roman numerals while also discussing some pedagogical applications. For the analysis of popular music especially, the Nashville number system arguably offers a more faithful, efficient, and flexible approach to representing functional harmonic syntax than is possible using traditional Roman numerals.
De Clercq, Trevor
"The Nashville Number System: A Framework for Teaching Harmony in Popular Music,"
Journal of Music Theory Pedagogy: Vol. 33, Article 1.
Available at: https://digitalcollections.lipscomb.edu/jmtp/vol33/iss1/1