Santa Clarita was incorporated in December 1987, but its history stretches back several centuries. About AD 450, the Tataviam arrived, numbering around 2,000 at their zenith.
The Santa Clara River was named by Spanish explorers for Clare of Assisi. The valley and the settlement later became known as "little Santa Clara" in deference to the Northern California mission and city of Santa Clara, California. In time, "little Santa Clara" became "Santa Clarita."
In 1842, Francisco Lopez made the first "documented" discovery of gold in California. The event is memorialized in an 1842 mining claim issued by Gov. Juan B. Alvarado. The discovery was made in Placerita Canyon, an area later used as Hollywood's original back lot.
The community of Newhall is named after Henry Newhall, a businessman who made his fortune during the California Gold Rush after opening up the H.M. Newhall & Company, a successful auction house in San Francisco. Newhall's next business interest was railroads. He invested in rail companies that would connect San Francisco to other cities and became president of the San Francisco and San Jose Railroad. In 1870, he and his partners sold the company to Southern Pacific Railroad, on whose board of directors he then sat.
After railroads, Newhall turned to real estate and ranching. He purchased a number of the old Spanish and Mexican land grants in the state for a total of 143,000 acres (58,000 ha) between Monterey and Los Angeles counties. The most significant portion was the 46,460 acres (18,800 ha) Rancho San Francisco in northern Los Angeles County, which he purchased for $2/acre, and which became known as Newhall Ranch after Newhall's death. Within this territory, he granted a right-of-way to Southern Pacific through what is now Newhall Pass, and he also sold them part of the land, upon which the company built a town named after him: Newhall. The first station built on the line he named for his hometown, Saugus, Massachusetts. After his death, Newhall's heirs incorporated the Newhall Land and Farming Company, which oversaw the development of the communities that now make up Santa Clarita.
On September 26, 1876, Charles Alexander Mentry brought in the state's first productive oil well at Mentryville, giving rise to the California oil industry. The oil was brought to a refinery at Newhall, now the oldest existing petroleum refinery in the world; it was operational from 1874 to 1888.