The guitar’s heaviest key — anchored on the lowest open string.
See how all seven chords sit together, and hear what makes each degree do its job.
Open E Major in the Studio →The key of E Major contains E, F#m, G#m, A, B, C#m, D#dim. In Roman numerals that's I, ii, iii, IV, V, vi, vii° — the tonic (E) is home, and the dominant (B) creates the tension that resolves back to it.
Because the guitar's lowest string is an E. The tonic sits right at the bottom of the instrument's range, so E chords ring with more low-end weight and sustain than anything else — which is precisely why so much rock and blues is written there.