Wildlife overpass designed for desert bighorn sheep (Ovis canadensis nelsoni), US Hwy 93, NW Arizona, USA. This particular overpass is about 30 m wide and it is the most northern of three wildlife overpasses in the area. It is situated at a ridge; desert bighorn sheep seem to want to cross US Hwy 93 primarily at ridges rather than at flat terrain or gullies. Therefore, for desert nighorn sheep, overpasses seem more appropriate than underpasses.