The method for writing chord charts known as the Nashville Number System was originally developed in the 1950s by Neal Matthews Jr. who was working with the Jordanaires, the vocal group best known for singing with Elvis Presley. Charlie McCoy, the legendary Nashville session player, is generally credited with perfecting the method and bringing it to widespread use in the studios of Nashville. In a nutshell, the number system is a way to write a chord chart that can be played in any key without transposition. The only thing required is knowledge of the intervallic relationship of a note within a key, because the numbers refer to the scale tone on which a chord is made. Ex. 1 is a typical chord chart in standard format, and Ex. 2 is the same chart in the Nashville Number System.
Because we’re in the key of F, 1 is an F major chord, 4 is Bb major (built on the 4th degree of the F major scale), and 5 is C (built on the 5th degree of the scale). An “m” next to the number makes it a minor chord. A “slash” chord, as in bar 2 is simply an inversion of some sort. For example, in bar 2 of Ex. 2, the chord indicated by 4/1 is the chord built on the fourth degree of the key (in this case a Bb) with the 1 in the bass (which, in this case, is an F), a Bb/F in standard notation—fairly intuitive. Similarly, in bar 12, the 5/7 chord is a C/E; that is, the 5 chord of the key (a C major chord) with the 7th degree of the key (an E in the key of F) in the bass. Compare the traditional chord chart to the number chart to see how they relate.
In the Nashville chart you’ll see chords with a #4 or b5 in them. These are extensions, just as you would expect if you saw them in standard notation. In the Nashville system, however, the first number written relates intervallically to the main key. So in bar 16 of Ex. 2, the 27/#4 indicates a G7 (the 2 chord in the key of F with a dominant 7th extension) with the #4 in the key of F (a B natural) in the bass: In other words, a G7/B in standard notation. Similarly, when you see 37#5 in bar 23, you would play an A7/C#.
The system took hold in Nashville for several reasons. First, in general, the harmonic content of the songs is fairly simple and diatonic. So it was easily represented and understood in this format. Second, it is very common for a singer to change keys (usually up or down a half step) in the course of a recording session. For anyone who’s ever had to transpose a written piece of music or traditional chord chart on-the-fly, it is easy to see how a number chart could be useful: Whatever key the song is in is represented by the number 1, and a number chart is always in the key of 1.
Note that bars 2 and 4 are being “pushed”—usually an eighth-or quarter-note anticipation of the chord. I wrote in the rhythm to indicate an eighth-note push, but different people notate this in different ways. Sometimes a > symbol is put just to the left of the chord to be anticipated, and it’s decided in the room whether it’s an eighth or quarter note push.
Nashville recording sessions are unique in that, in general, they are a true collaboration between the artist, the producer, and the musicians. On a session, the chart would be read by everyone, but each musician would compose their own part based on the road map given to them. As a pianist, I would look at this map after hearing the demo of the song (or maybe the artist playing it in the room for us), and play what I think is appropriate for the record: I will decide what inversions to play, how much or little I play, what my comping rhythm is, and so on.
The rhythmic and harmonic information on the chart will need to be honored (I won’t play a 7b9 where only a 7 is written, or disregard a notated rhythm). But the way I play the chords and rhythms within that framework is up to me. The producer and artist will have varying levels of input in this depending on who they are and what the situation is.
As you can see, the number system is very intuitive and “gut” based. As a result, it allows you to keep the creativity flowing as you hone in on the more important aspects of a song, such as the vocal performance and the arrangement.
“The number system does have its limits. As a piece of music gets more complicated, there is a point at which standard ‘lettered’ chord symbols are required,” says Matt Rollings, an acclaimed keyboardist, composer and producer based in Nashville, Tenn. Rollings has performed on countless recordings and onstage with artists such as Lyle Lovett, Mark Knopfler, and Mavis Staples. Most recently, he co-produced the new Willie Nelson album of George Gershwin songs entitled Summertime. Find out more at mattrollings.com.