Nashville number system
A method of charting music using numbers instead of letter names, enabling instant transposition.
In Depth
The Nashville number system represents chords as scale degrees: 1 is the tonic, 4 is the subdominant, 5 is the dominant, and so on. This means a chart written in numbers works in any key without rewriting. A singer says the song is in E flat, and the band simply plays their 1-4-5 pattern starting from E flat. The system was developed by Nashville session musicians in the 1950s and remains standard practice in country, gospel, and commercial music recording.
Neal Matthews Jr. of the Jordanaires developed the Nashville number system, and session musicians adopted it so thoroughly that many Nashville players struggle to read traditional notation.