SR 57 begins at the Orange Crush interchange near downtown Orange
SR 57 begins at the Orange Crush interchange near downtown Orange, where it meets the northwest–southeast Santa Ana Freeway and the east–west Garden Grove Freeway(SR 22). The Orange Crush interchange, which had long been considered a major bottleneck, was rebuilt in the 1990s and 2000s. The freeway heads north from the junction and soon crosses to the west side of the Santa Ana River, continuing north through suburban portions of Anaheim and passing next to Anaheim Regional Transportation Intermodal Center, Angel Stadium and Honda Center. In northern Anaheim, SR 57 meets the Riverside Freeway (SR 91). SR 57 briefly passes through Placentia and Fullerton, providing access to California State University, Fullerton. As it crosses Imperial Highway (SR 90) near the Brea Mall and enters Brea, SR 57 enters more rugged terrain before climbing through Brea Canyon, the gap between the Chino Hills and Puente Hills. Near the rim of the canyon, the highway curves north out of the Brea Canyon, and descends slightly to a junction with thePomona Freeway (SR 60) in Diamond Bar, right on the edge of the San Gabriel Valley.
A short overlap carries SR 57 traffic on the same roadway as SR 60. The two routes head northeast through an arm of the San Gabriel Valley; after they split, SR 57 ascends slightly and then slopes through the edge of the Puente Hills and into the west end of the Pomona Valley. Here it meets the San Bernardino Freeway (I-10) and Chino Valley Freeway (SR 71) at the four-level Kellogg Hill Interchange. In the north half of that interchange, SR 57 enters the San Jose Hills, climbing to its highest elevation before descending back into the connected San Gabriel and Pomona Valleys and ending at the Glendora Curve interchange with the Foothill Freeway (I-210) in Glendora.
High-occupancy vehicle lanes (HOV) exist in the median of SR 57 south of SR 60 in Diamond Bar. Elevated ramps allow HOV traffic bound to or from Brea Canyon to connect with I-5 towards the southeast, SR 91 towards the west, or SR 60 towards the east without entering the main lanes.
SR 57 is legally eligible for the State Scenic Highway System through Brea Canyon, between SR 90 and SR 60, though it has not officially been designated by Caltrans as such because it has not successfully been through the nomination process. The entire route is in the California Freeway and Expressway System, and is a freeway for its entire constructed length. SR 57 is also part of the National Highway System (NHS), a network of highways that are essential to the country’s economy, defense, and mobility. The highway from SR 1 to SR 60 in Diamond Bar is officially designated as the Orange Freeway.In 2013, SR 57 had an annual average daily traffic (AADT) of 129,000 between SR 60 and Sunset Crossing Road in Diamond Bar, and 278,500 between SR 91 in Anaheim and Orangethorpe Avenue in Placentia, the latter of which was the highest AADT for the highway.