Interstate 605 is a 27-mile-long (43 km) major north–south auxiliary Interstate Highway in the Greater Los Angeles urban area of Southern California. It runs from I-405 and State Route 22 (SR 22) in Seal Beach in Orange County to I-210 just south of the Irwindale–Duarte border in Los Angeles County. The San Gabriel River Freeway closely parallels the San Gabriel River for most of its alignment, hence its name, which is one of the few Southern California freeways not named after a city along its route.

The Whittier Narrows is a narrows or water gap in the San Gabriel Valley of Los Angeles County, California, United States, between the Puente Hills to the east and the Montebello Hills to the west. The gap is located at the southern boundary of the San Gabriel Valley, through which the Rio Hondo and the San Gabriel River flow to enter the Los Angeles Basin. The Narrows is located near the convergence of Interstate 605 and California State Route 60.