The Eastshore Freeway was created in the mid 1950s (construction commenced in 1954, last segment completed May 10, 1960) by re-engineering the Eastshore Highway, a thoroughfare constructed in the 1930s (1934–37) as one of the approaches to the Bay Bridge and designated as part of U.S. Route 40. The Eastshore Highway began in El Cerrito at an intersection with San Pablo Avenue at Hill Street between Potrero Avenue and Cutting Blvd., adjacent to the location today of the El Cerrito Del Norte station of BART. It was not a freeway in that access was at intersections with adjoining streets rather than by ramps. The Eastshore Highway ran from El Cerrito to the Bay Bridge along the same routing as today's freeway, although it was much narrower. A causeway was constructed for this purpose by filling in part of the mudflats along the bayshore. In the stretch from University to Ashby Avenues in Berkeley, this resulted in the creation of an artificial lagoon which was developed by the Works Progress Administration in the late 1930s as "Aquatic Park".