US 99, known as “The Old Road” in the Santa Clarita area, has had a varied past. It was first built through this area in 1930 as a three-lane highway. This roadway, known then as the Newhall Alternate, would be the first of many versions of the road through this pass.
In 1949, the roadway was temporarily widened to four lanes by restriping and adding some paving to the shoulder. This was done as the real work to upgrade the highway wouldn’t commence for a couple of years. Evidence of this widening can still be seen today.
In 1951, US 99 was realigned and finally upgraded to an expressway, though this would not last long. Just south of this point, the highway was realigned again to accomodate a new freeway from the Tunnel Station Junction (US 6 and Foothill Blvd) to Sepulveda Junction (State Route 7). This freeway still exists today in part and serves as the “Truck Route” through the pass.
Starting in 1967 and ending in 1975, the pass was yet again the site of major construction. This time, little of the old highway would be utilized as the new route of Interstate 5 bypassed much of the existing route. Where it didn’t bypass the alignment, it was torn up and completely replaced with the current roadway.
US 99 would, however, serve as the main route one last time following the January 17, 1994 Reseda / Northridge earthquake. Portions of I-5 collapsed during the earthquake, resulting in a need for a quick replacement. The resulting detours created an alignment very similar to the pre-1967 highway, giving motorists (albeit not with joy) a chance to drive old US 99 again. Upgrades were made to the highway through the pass including repaving, guardrail, and a temporary prohibition on left turns. Sadly, for highway historians, this resulted in the loss of the 1951 concrete and some curbing. It is a price to pay to help keep California’s Backbone functioning during a crisis.