the city of San Diego again. Once on the mainland, SR 75 has a northbound exit to National Avenue and a southbound entrance from Cesar E. Chavez Parkway. Through traffic is directed onto I-5 south or north in Logan Heights, where SR 75 ends. SR 75 is eligible for the State Scenic Highway System. It is officially designated as a scenic route for nearly its entire length, from the Imperial Beach city limit to Avenida del Sol in Coronado, and the portion across the Coronado Bridge meaning that it is a substantial section of highway passing through a "memorable landscape" with no "visual intrusions", where the potential designation has gained popular favor with the community. SR 75 is also part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration. In 2013, SR 75 had an annual average daily traffic (AADT) of 66,000 on the Coronado Bridge (the highest AADT for the highway), and 16,000 between Rainbow Drive and 7th Street in Imperial Beach (the lowest AADT for the highway). History Construction The intersection of Third Street and Orange Avenue dates back to at least 1890. The process of paving portions of Orange Avenue began in 1893, with an estimated cost of $50,000 (about $ in dollars); of sidewalks were also included. The plan was to make the avenue "one of the most beautiful in Southern California." From Palm City to Imperial Beach, the road was paved by 1920. The Silver Strand Highway opened in 1924 during a festival at the Tent City summer resort in Coronado, and went from Coronado to Palm City. By 1928, all streets in the city of Coronado had been paved, which was expected to encourage people to visit Tent City. Plans to transfer the Silver Strand Highway to state maintenance were in place as early as November 1931, and were to take effect once Silver Strand State Park was completed and open. In 1933, the highway from the San Diego–Coronado Ferry to Route 2 (now I-5) was added to the state highway system, and was designated as Legislative Route 199 two years later. By that same year, Sign Route 75 was posted from U.S. Route 101 (US 101) in Palm City to the ferry landing. After a subsequent highway project around 1939, SR 75 passed through Tent City and,