Historical Tour of old US 99

- Five Mile Grade : Castaic

Five Mile Grade from Castaic. Concrete in foreground marks one of the Palomas Creek bridges from 1951.

Truck Escape Ramp in 1968 before the new southbound lanes were opened. Note the downhill traffic still using the roadway. Photo Courtesy - Gordon Glattenberg

Map of the Truck Escape Ramp.

US 99 started its climb over the Liebre Mountains here. This grade is five miles long - hence the name. Both sides of the highway once went on this side as evidenced by the Truck Escape Ramp further up. That ramp, constructed in 1958, was heavily used until January 20, 1970 when the new southbound lanes for I-5 were opened.

This segment of I-5 is very unusual as the northbound and southbound sides have been switched. Northbound, which uses the old grade US 99 used, is west of the southbound lanes. A completely new roadway was built for the southbound lanes on a different ridge east of the old grade.

This map shows all of Five Mile Grade from Castaic to Violin Summit. Note the two crossovers on each end of the grade.

This section was completed in 1933, widened to four lanes in 1948, and converted to a freeway from 1968-1970.

This photo shows the highway in 1948 near the top of the grade just after it was widened.

About 2/3 up the grade, the highway split for a short distance as this map shows. The roadway to the right is the 1933 alignment and to the left is the 1948 widening. When Five Mile Grade was redone as a freeway, the split was removed and the new roadway took the 1948 side. The 1933 side was then buried and torn up.

Go North on US 99 to Bakersfield

Go South on US 99 to Los Angeles

Return to US 99 Introduction Page