Other principal routes in the region include State Route 99, which runs along the valley's eastern edge, roughly parallel to I-5, from Sacramento until its northern terminus in Red Bluff; State Route 20, which traverses the valley from west to east on its route from State Route 1 in Mendocino County to the Donner Pass; State Route 49, named in honor of the California Gold Rush and running through many old mining towns in the foothills of the valley; and State Route 45, which runs along the course of the Sacramento River roughly ten miles (20 km) east of I-5.