Federal Highway Administration. It is officially designated as the Robert T. Monagan Freeway after the California legislator who represented the area from 1961 to 1973. History When the Department of Engineering laid out the initial state highway system after the state's voters approved a bond issue to pay for it in 1910, they included Route 5, connecting Santa Cruz and Oakland with Stockton via Altamont Pass. San Joaquin County paved the portion near Tracy with asphalt with their own bond issue, passed in 1909, and the state later resurfaced it with concrete. In addition, the new concrete road bypassed Banta, which the old county road had passed through via Banta Road, F Street, and Grant Line Road. Otherwise, the road was relatively direct, coming down from Altamont Pass onto Grant Line Road, following Byron Highway into Tracy, and leaving east and northeasterly on 11th Street to the San Joaquin River at the Mossdale Crossing. The Lincoln Highway Association chose this route in 1913 for their transcontinental highway, where it remained until the Carquinez Bridge opened in 1927, creating a shorter route via Vallejo. In 1926, the American Association of State Highway Officials designated the Stockton-Bay Area route as US 48, which was absorbed by an extension of US 50 by the early 1930s. A 1938 four-lane bypass of the old road around Altamont Pass was extended east to Tracy as a four-lane expressway on November 16, 1954. By then, the entire route between the Bay Area and Stockton was four or more lanes, following the present I-580 (eastbound lanes where they separate), I-205, 11th Street, and I-5 from Livermore through Tracy to Stockton. During early planning for the Interstate Highway System, the main north-south route through California (now I-5) was to use SR 99 through the San Joaquin Valley; a connection to the Bay Area split near Modesto and roughly followed US 50. The Bureau of Public Roads approved a move to the proposed Westside Freeway in May 1957, and in November they added a North Tracy Bypass that would connect I-5 and I-580. Construction began in the late 1960s, incorporating part of the 1954 expressway and a new alignment bypassing Tracy to the north, and the $14 million road opened to traffic on December 21, 1970. (A short piece at the west end, including the bridge over the California Aqueduct, was upgraded several years earlier when I-580 and I-5