Built in the 19th century, the Pioneer Oil Refinery in Newhall played a pivotal role in the early development of the Santa Clarita Valley. As the first successful oil refinery to be built and operated in California, the refinery was recently added as a Historic Site in the National Register of Historic Places and has been listed in the California Register of Historical Resources. The Pioneer Oil Refinery was built by California Star Oil Works (later Chevron) in 1876 and was used to process oil discovered in Pico Canyon until around 1888 when its use was changed to instead provide water to the oil drilling operation at Pico Number 4 in Mentryville. The first historical recognition for the refinery came in 1930 when the site was recorded as California’s first commercial oil refinery.