Tonality
The symphony's first movement is in C minor, and the finale concludes in E♭ major, the relative major of C minor. Thus, the work exhibits progressive tonality; as a result, a titular description in terms of a single key is not realistic, and is not found in serious works of reference.
The symphony is sometimes described as being in the key of C minor; the 'New Grove Dictionary of Music and Musicians', however, represents the progressive tonal scheme by labelling the work's tonality as 'c--E♭'
Read more about this topic: Symphony No. 2 (Mahler)