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