Opened in 1915, The Ridge Route was California’s first mountain highway and the super highway of its day. Some credited it, for better or worse, with saving the state from being divided into two separate states. Built, graded, and paved for about $1,500,000, it was considered one of the most scientifically constructed mountain roads in the world. Running from Castaic in the south to Grapevine in the north, it was 48 miles long and contained 39,441 degrees of curves, roughly equal to 110 complete circles. Its strictly enforced speed limit was 15 MPH. In 1933 it was replaced by the Alternate Ridge Route, later known as US 99, which was in turn replaced by I-5 in the 1960s.
