State Highway 45 is a highway loop around Austin, Texas, that exists in two open segments. The official designation of SH 45 is such to form a complete loop around Austin, a distance of roughly 80 miles (130 km). The other segment is a toll road that forms a backwards C-shape along the boundary of Travis and Williamson County before bending down along the eastern edge of the Austin metropolitan area where it shares its route with SH-130.