In Flight

Perfunctory wing photo... I often take photographs to see if I can determine where the geographic features I'm seeing are located, but this kind of has me stumped. It might be Lake Mead near Las Vegas (it looks like a dammed up river to me), but the shape doesn't quite fit with what Google Maps depicts. Also, I'm not so sure that the Chicago-to-San Francisco flight path goes as far south as Las Vegas.