By the early 1930s, growing automobile traffic in Sacramento had outgrown the capacity of the Sacramento Northern Railway Bridge, prompting recognition of the need for a new M Street crossing linking one of the city's busiest routes to U.S. Highway 40. During the Great Depression, funds for the project came through a joint effort by Sacramento and Yolo Counties, the State of California, and the federal Civil Works program as part of New Deal infrastructure work. In early 1934, the California Division of Highways Bridge Department and the state's Division of Architecture began plans for a new vertical-lift bridge, with Fred W. Panhorst and George Thompson as structural engineers and Alfred Eichler as designer. Eichler conceived the bridge in the Streamline Moderne style, with a rail line in the center of the deck, two traffic lanes on either side, and pedestrian walkways. George Pollock & Company dismantled the old M Street Bridge and built the new structure in the summer of 1934, employing an average of 130 workers for 16 months. The 737-foot bridge included a 209-foot vertical-lift section that could rise nearly 100 feet above the Sacramento River, and as the first vertical-lift span bridge on the California highway system, it also used an experimental lightweight concrete later used in the San Francisco-Oakland Bay Bridge. Named for its streamlined towers, it was designed as a gateway to Sacramento and the state Capitol, opened to traffic on December 15, 1935, was recognized in 1936 by the American Institute of Steel Construction as "The Most Beautiful Bridge," and in 1982 was listed in the National Register of Historic Places for its significance in architecture, engineering, and transportation.