California State Route 238

California State Route 238 is a north-south highway in Alameda County that connects Interstate 680 in Fremont to Interstate 580 in Castro Valley. The road consists of a mix of surface streets and faster sections that pass through several East Bay communities.

The route received its current designation in 1964, replacing the former State Route 9. Later sections were integrated into Interstate 238, reflecting the region's evolving transportation infrastructure.

A section called Mission Boulevard runs past Mission San José, a location important to the area's early Spanish colonial period and settlement history.

The route facilitates travel between several East Bay communities and alternates between regular city streets and faster roadways. Drivers should expect varying speed limits depending on the time of day and section.

The roadway alignment follows the Hayward Fault, a major geological feature running through the eastern San Francisco Bay Area. This alignment with an active fault line subtly shapes the region's physical infrastructure.