Highway 1

State Highway 1 (officially "California State Route 1") is the longest state highway in California, running near the Pacific coast for the entire northwest-southeast length of the state. It enters Santa Cruz County from Monterey County, crossing the Pajaro River in the southeast near Watsonville, and exits to San Mateo County in the northeast past Waddell Creek. The highway roughly follows the route of the first European explorers to pass through the area that is now Santa Cruz County, the Spanish Portolá expedition of 1769. In Santa Cruz, a non-freeway portion of the highway is called Mission Street. The state also gave the Central Coast portion of Highway 1 the name "Cabrillo Highway", which makes no historical sense and is rarely used by locals.

Only one state highway originates elsewhere on both ends and passes through Santa Cruz County: Highway 1. Five highways originate in Santa Cruz County and pass out of it: Highway 9, Highway 17, Highway 35, Highway 129, Highway 152. One begins and ends within the county: Highway 236.