San Dimas Local History - LA County Library

As long ago as 1000 B.C., Gabrielino Indians were thought to be the first inhabitants of the region that became San Dimas, though some archaeologists have found evidence that other Indians tribes lived there 7,000 years ago. Spanish frontier soldier Juan Baptista DeAnza and his party were the first white people to pass through the area when, in 1774, they stopped in what later became Mud Springs en route from Mexico to Monterey. More than half a century later, Jedediah Strong Smith was the first American to come overland when he camped in the region on a beaver-trapping expedition. Inhabitants started putting down roots there little more than a decade later when, in 1837, Ygnacio Palomares and Ricardo Vejar started the Rancho San Jose as part of a Mexican land grant. Between 1872 and 1870 Dennis Clancy and his wife ran a stage station near Mud Springs and their children were the first Americans born there after California joined the Union in 1850. The Teague family, whose citrus nurseries would become world-famous, arrived in 1878 and planted their first citrus trees the following year.

The town of San Dimas began in 1887, a product of Southern California’s great land boom. This boom was one of four such bursts of population and development in the southern part of the state in the half century between 1876 and 1923. Among the major reasons for the land boom was completion of a transcontinental railroad as well as more localized rail expansion. For San Dimas, the catalyst for development in 1887 was completion of the Santa Fe Railway’s main line through the area. In short order, the San Jose Ranch Company was created and began to lay out plots of land and streets in the town. More development followed in a fast domino effect, and by 1890 San Dimas had a planing mill, a hardware store, and fourth-class post office at the corner of Bonita and Depot, a brick kiln at the corner of Amelia and Cienega, two pipe yards, and its first telephone and restaurant. The community grew as an agricultural region, though its crops gave way to houses and other development by the middle part of the 1900s.

As early as 1912 the Board of Trade talked about incorporating as a city, but following a year of discussion and dissension they dropped the idea. Residents’ desire to incorporate came back in the late 1950s, after adjacent communities began encroaching on San Dimas through annexation. On June 28, 1960, San Dimas voters cast a majority of ballots to incorporate as a city, a decision that became official on August 4, 1960. San Dimas became the 70th city in Los Angeles County.