The historic Ridge Route was a two-lane road built in 1914-1915 by pick, shovel, and mule-drawn Fresno scrapers, with its ridge alignment chosen to avoid drainage problems and reduce earthwork. Its ridge section formed an almost continuous series of short-radius reversing curves, 697 curves in 36 miles, and it became the first highway crossing of a major mountain range by the newly formed California State Department of Highways. As the first primary highway connecting Northern and Southern California, it was a major factor in keeping the state from dividing into two states with the Tehachapi Mountains as the border between them. In 1933, the opening of Highway 99 to the west moved the original roadway off the ridge, and later upgrades and additions in 1933, 1952, and 1968 created the 8-lane divided freeway Interstate 5. The 1933 and 1952 roadways now lie beneath Pyramid Lake. Beginning in 1915 as a 2-lane gravel road with a 15 M.P.H. speed limit, it later became an 8-lane concrete-paved full freeway with a 65 to 70 M.P.H. speed limit, reducing the trip between Los Angeles and Bakersfield from about 10 hours to less than 2 hours.