Up Cork or Up (?)

Posted by SR on December 17, 2004

What is the origin of 'up' as a shout of support or encouragement? I remember shouting 'Up Cork' as a sign of support for the Cork teams in hurling or football when I was young. Is this a phrase used only in Ireland or is it still in common usage anywhere else?
Why 'up?'
I haven't heard it used much here in the US except as a toast in some Irish pubs.