The highway begins from the south on Los Santos Blvd, at the intersection with the Del Perro Freeway in East Vinewood. It begins as a six lane urban freeway traveling through northeast, intersecting the Racetrack and Vinewood Bowl. It then begins to turn north while narrowing to a rural four-lane freeway at the Route 18 interchange, as it skirts along the western edge of the Tataviam Mountains. This part is co-signed with Route 13. At the intersection of the Palomino Freeway, I-1 loses its concurrency, and the freeway continues as the Senora Freeway .