Since 1797 the route of the old padre trail through this area provided a key link to the coast for Mission San Miguel and the lower Salinas valley, especially in the 1860's for the shipping of mercury, vital to the recovery of California's gold.
During the mid 1800's settlers and entrepreneurs flooded into the area, including Auguste and Pauline Dubost who arrived from France in 1882 and opened a blacksmith shop. He moved the Adelaida Post Office to this site in 1889 and became postmaster. He then proceeded to operate a general store, acquire interests in mines, run a portable steam engine to power threshing machinery and a saw mill and had a lime kiln operation for plaster and mortar used in Paso Robles construction. Late word of his daughter's death, while on her honeymoon to Los Angeles in 1908, resulted in him cofounding the Adelaida Rural Telephone Company, maintained and owned by grandson Raymond Dubost until 1960. By his death in 1917 Auguste Dubost had accumulated nearly 4000 acres of Adelaida ranchland.
During those halcyon days Adelaida supported six schools, three post offices, three churches, two dance halls, two stores and perhaps 700 people producing livestock, grain, lumber and mining mercury. With the arrival of the railroad in Paso Robles and fading of the mining era, the need for coastal access was minimized and the area declined with most of the 180 homesteads consolidated into large ranches. Today, Adelaida again flourishes with wine production, orchards, ranching and farming activities, idling in quiet reverie of his heyday years in the late 1800's.