The road became popular as a route east during the California Gold Rush. The Butterfield Overland Mail ran along this route from 1858 to 1861. A portion of Route 152 from Bell Station to Pacheco Pass was a toll road from 1857 until 1878. In that year, Merced County and Santa Clara County purchased the toll road and replaced it with a new road built as a public highway, part of which is now a segment of Whiskey Flat Trail in Pacheco State Park. In 1915, the road became part of the state highway system, and in 1923, the state built the third road through the pass. Historic references say the portion of the route west of SR33 was named Legislative Route 32 before being designated State Route 152.