The Wednesday morning commute on Highway 99 was backed up around Keyes after five vehicles collided into each other in chain-reaction fashion.
No significant injuries of drivers or passengers were reported in the 7:45 a.m. pile-up, but hundreds of drivers were forced to inch their way toward their destinations.
The crash took place in the northbound lanes south of the Keyes Road overpass but a substantial amount of rubber-necking by southbound motorists caused delays there as well.
Speed was believed to be a factor in the chain of rear-end crashes, said an official with the California Highway Patrol. Weiman Ohlhausen, 79, of Arizona, was driving a Ford F-250 pickup, when he rear-ended a Ford Explorer driven by Jessica Luna, 22, of Turlock. Other vehicles involved a Ford Fusion driven by Patricia Alcaraz, 48, of Turlock; a Toyota Tacoma driven by Brock Longacre, 32, of Modesto; and a Ford Focus driven by Jessie Gonzales, 52, of Winton.
A number of cars had to be towed from the scene.
Lanes of traffic were opened by 8:33 a.m.
Alcohol was not a factor.