The blues: 12-bar blues and improvising

The blues began in African American communities in the southern United States around the end of the 1800s. It went on to shape jazz, rock and roll, rock and pop.

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Where the blues came from

The blues grew from African American work songs, field hollers and spirituals in the southern USA, especially around the Mississippi Delta, in the late 19th and early 20th centuries.
Its songs often express hardship and sadness, but also humour and resilience.
Famous blues musicians include Bessie Smith and B.B. King. The blues strongly influenced jazz, rhythm and blues, rock and roll and rock.

The 12-bar blues

The 12-bar blues is a chord pattern 12 bars long, using chords I, IV and V:
The second row shows the chords in the key of C. The pattern then repeats.
Bars 1 to 4Bars 5 to 8Bars 9 to 12
I I I IIV IV I IV IV I I
C C C CF F C CG F C C

Blues features

Blue notes: flattened (lowered) 3rd, 5th and 7th notes, which give a bluesy sound.
The blues scale on C: C, E flat, F, F sharp, G, B flat, C.
Lyrics often follow an AAB pattern: a line, the same line again, then an answering line.
Walking bass: a bass line that moves on every beat, often by step.
Swing rhythm and improvisation are common, with call and response between the singer and instruments.
Worked example

Write out the 12-bar blues in G major (I is G, IV is C, V is D).

  1. The pattern is I I I I, IV IV I I, V IV I I.
  2. Replace I with G, IV with C and V with D.
  3. G G G G, C C G G, D C G G.

Answer: G G G G | C C G G | D C G G

Key idea

The blues began in African American communities in the southern USA. The 12-bar blues uses I I I I, IV IV I I, V IV I I. Features include blue notes, the blues scale, AAB lyrics, walking bass, swing and improvisation.

Key words
12-bar blues
I I I I, IV IV I I, V IV I I.
Blue notes
Flattened 3rd, 5th and 7th notes of the scale, typical of the blues.
Chord
Two or more notes played at the same time.
Call and response
A leader plays or sings a phrase (the call) and a group answers (the response).

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Quick check

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Extra practice

2 more questions

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  1. The blues grew out of which earlier types of music?

    1. Work songs and spirituals
    2. Baroque concertos
    3. Gamelan
    4. Samba
    Show the answer

    Answer: Work songs and spirituals

    African American work songs and spirituals.

  2. How many bars long is the standard 12-bar blues chord pattern?

    1. 8
    2. 16
    3. 4
    4. 12
    Show the answer

    Answer: 12

    It is in the name.

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Sources and references

Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.