Why does the viola need its own clef?

I play the French Horn so I am used to treble/bass clef and I have a bassoonist friend so I know about tenor, but I am curious as to why the viola needs the alto clef. The alto trombone used it too, but that instrument is almost extinct. As you can tell I spend too much time on these sorts of things.

Why does the viola need its own clef?
For the range of the instrument, it minimizes ledger lines.
Reply:I dunno. If I were inventing the viola and it's music from scratch, I'd use the tenor-g clef, which looks like a normal g-clef with a little 8 under it, indicating that it's an octave below what it appears to be. This puts middle c' on the 3rd space and avoids ledger lines just as well as the perverse alto clef.


However, when I took up viola after 50 years of reading piano bass and treble clef, I just said "Stop complaining about it. Just shut up and DO it." That saved me a lot of trouble, really!
Reply:The clef just decribes what range of pitches you are looking at. Some instruments use clefs other than treble or bass to make the notation simpler to read. It is just a convenience to the player basically.
Reply:There would be too many leger lines if it used the treble or bass clef. It's range is in between so it uses the alto. Even worse is "transposed" instruments like Bb clarinet - when their music reads "C" they are playing a Bb. If they want to play in key from regular sheet music, they have to transpose the whole piece.