Baa Baa Black Sheep

So, here's the thing. The other day I had a Gyros (I looove those things!) and it was made with lamb. My dog eats dog food with lamb and rice. There are lamb chops, rack of lamb and just plain ol' meat called 'lamb'.

My question is this: where did all the mutton go? Are we (and by 'we' I'm not speaking the royal we -for probably the first time ever - but the collective and societal 'we') no longer supplying the American public with mutton? Or is it simply that all sheep are now referred to as lamb regardless of age?

I honestly don't know and would very much like to. (And now you know what it is I do at work - sit around and think of stuff like this.)