Interstate 505, originally Interstate 5W, is a spur route of Interstate 5 that runs 33 miles from Interstate 80 at Vacaville in Solano County to I-5 just southeast of Dunnigan in Yolo County, along the western edge of the Sacramento Valley. It provides a bypass of Sacramento for drivers going between the San Francisco Bay Area and northern California's Shasta Cascade, as well as Oregon and beyond.