Highway 236
From Santa Cruz County history wiki
State Highway 236 (officially "California State Route 236") forms an 18-mile loop the begins (in Boulder Creek) and ends at Highway 9. The road provides access to Big Basin Redwoods State Park. Locally, the highway is known as Big Basin Road.
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.