Because of its location at the southernmost end of the San Joaquin Valley, the interchange is a major hub for traffic between the Los Angeles area and the valley. As the Golden State Freeway, I-5 approaches from the south after descending from the Tejon Pass in the Tehachapi Mountains. At the split, SR 99 heads roughly due north to Bakersfield, Fresno, and the other population centers in the valley. I-5 then continues as the Westside Freeway to the northwest toward the western part of the valley, to serve as a faster route to San Francisco, Sacramento, and other Northern California destinations.