"Magnetic Rag" was written by an ailing Joplin near the end of his career, when interest in ragtime was waning.

Possibly as a result of Joplin's mood at this time, the piece expresses a melancholy almost entirely unheard in his earlier works.

His publishing it in 4/4 was simply a way to connect the rag with classical and popular piano works of prior fame.

[6] Since Joplin published "Magnetic Rag" himself, it has been suggested that the composition fully reflected his wishes and contained no compromises.

It was at this time that Joplin attempted to write rags that were not confined to the standard "oom-pah" left-hand beat and that incorporated several other novelties.

This shift demonstrates one of Joplin's late-life techniques: establishing a foreign key within the framework of a strain.

The darkening[9] tone generated by the minor scale stands out among Joplin's rags, and is revisited in the D strain.

In contrast to the minor themes in the B strain, the third section is upbeat but with bittersweet harmonies,[10] returning once again to the key of B-flat major.

[11] The C strain also represents the only known time when Joplin departs from the standard sixteen-bar form, being instead 24 bars in length[5][12] with an uneven 14- and 10-bar division.

[15]Some music historians evaluate "Magnetic Rag", as well as other works from Joplin's late period, as being indicative of his unstable mental condition which resulted from the effects of syphilis.

[16]In This Is Ragtime, Terry Waldo criticizes this view: To see Joplin's late rags as a "strange collection of contradictions" .

Jazz, seeking one theme as a center for improvisation, tended to weaken the sense of form that it inherited from ragtime.

One has only to hear the blazing return of the first theme of Magnetic Rag—the restoration of major tonality, the momentum of the renewed beat—to recognize the power of recapitulation in ragtime.

Rifkin speculates that the composition's short coda also "seems like a farewell, as if he knew how brief and bleak was the time still allotted him.