The bridge is on the Verde River about 75 miles NE of Phoenix. Sheep owners have rotated the herds from the mountains to the Valley [Phx is called the Valley of the Sun] to avoid the heat of the summer and the cold of winter forever. I remember growing up in the 1940's, the herds of sheep all around the little town in the West Valley where I grew up. My friend Jeep and I used to hang out with the Basque sheep herders who lived in little Tee Pee type canvas tents out in the fields. They always had a pot of beans going and mutton. They would feed us, probably because they were lonely and enjoyed having company. Below is a You tube video of part of the journey to the mountains.

http://www.youtube.com/watch?v=m3RBV76ivvs&feature=related