Over which chords does the blues scale fit???

Well, a debatable question!  But, if you think about it, the blues scale has a minor 3rd in it….so the first is: any minor triad or minor 7th chord….

The scale has a minor 7th so even a dominant 7th fits fine….

Also, the blue scale could even sound well over an altered chord since the minor 3rd will be heard as the #9 note of the chord….

So, in essence: a blues scale has a dominant 7th sound to it as well as a minor chord quality.  Therefore, what chords could one play on say a Bb blues scale???

Here they are:  the 1 - 4 - 5 chords in a minor 7th quality…and a 1 - 4 - 5 progression as well in a dominant 7th sounding quality!

There you have it one scale = 6 possible chords :)