State Route 91, also known as simply The 91, is a major east-west freeway located entirely within Southern California and serving several regions of the Greater Los Angeles metropolitan area. Specifically, it runs from Vermont Avenue in Gardena, just west of the junction with the Harbor Freeway (Interstate 110), east to Riverside at the junction with the Pomona (State Route 60 west of 91), Moreno Valley (State Route 60 east of the 91), and Escondido (I-215) freeways. The route is part of the California Freeway and Expressway System, and, since the portion west of Vermont Avenue was relinquished to local governments, it is entirely a freeway. SR 91 is part of the State Scenic Highway System from SR 55 to the east city limit of Anaheim, in the western part of the Santa Ana Canyon, and is eligible for the system through the canyon to I-15.
Although SR 91 is an east-west road, it inherited its odd (as opposed to even) route number from the now mostly decommissioned U.S. 91 which passed through the Inland Empire in a northeasterly direction on its way to Las Vegas, Salt Lake City, and points beyond. Those segments of U.S. 91 are now parallel to, or have been replaced altogether by, Interstate 15 (I-15).
