the san mateo–hayward bridge (commonly called the san mateo bridge) is a bridge crossing the u.s. state of california's san francisco bay. it provides a link of the san francisco peninsula with the east bay. the bridge's west end is in foster city, a suburb on the eastern edge of san mateo. the east end of the bridge is in hayward. it is the longest bridge in california and the 25th longest in the world. the bridge is owned by the state of california, and is maintained by caltrans, the state highway agency. further oversight is provided by the bay area toll authority.