turkey vulture or bald eagle. probably too big for most hawks. if the underside of the wings is half black/half silver, it's a turkey vulture. from the picture, not much coloration visible on the underside, though. edit: if the bird is facing away from the camera, ie, we are looking at the top of its wings, this is a turkey vulture. head looks more like a vulture than an eagle, too.
more edit: with the wings held that way, vulture.
If it was a turkey vulture wouldn't the head be red and featherless?
The underside of the wings were half black/half silver, its gotta be a vulture.