Before the Dumbarton and San Mateo-Hayward Bridges were built across the San Francisco Bay in the 1920s, San Francisco was bottled up at the north end of a long peninsula, with driving south on El Camino Real towards San Jose as the only reasonable alternative to the ferries for crossing the bay. The first of several highways built as an alternate to El Camino Real was the Skyline Boulevard, which was added to the state highway system in 1919. A second route, the Bay Shore Highway (Route 68), became a state highway in 1923, but only from the San Francisco city limits into San Mateo County, where the Dumbarton Bridge would begin. Just prior to the start of construction on the Dumbarton Bridge, San Francisco Supervisor Richard J. Welch noted that the Bay Shore Highway would need to be built all the way to San Jose as an escape valve for the additional traffic that the bridge would attract. Groundbreaking ceremonies were held in South San Francisco for the Bayshore Highway on September 11, 1924. The route used a right-of-way that was wide with a four-lane undivided highway wide.