The overland emigration to California from the east coast of North America began in 1841 when a small group of settlers left the already established Oregon Trail to follow the Humboldt River across Nevada and finally over a high mountain pass in the Sierra Nevada to Sutterís Fort. John Sutter constructed the fort in 1834 on a land grant from the Mexican government. The fort became the focus point for Anglo development in northern and central California in the 1840s. The city of Sacramento would grow up around Sutterís Fort and become the capital of the new state of the United States of America in 1847. Sacramento is about 75 miles west of Rubicon Springs.
Each summer after 1841 brought a few more settlers to California over the Sierra Nevada Mountains. By 1845, more than 250 people had made the trip. In the fall of 1846, a group of emigrates traveling by covered wagon gave their name "The Donner Party" to the high mountain pass and alpine lake when they became stranded there for the winter. Donner Pass is fewer than 20 miles north of Rubicon Springs. The somewhat orderly and sometimes fatal westward movement changed after the discovery of gold in 1848, when the hundreds of seasonal travelers changed to thousands. By the end of 1849, more than 40,000 people were working in the California mines. The gold rush to California brought the founders of Rubicon Springs and most of the next generation of owners to settle and seek their fortune in California.
The gold rush to California was set in motion in January, of 1848, when John Marshal discovered gold. He was building a water powered saw mill for John Sutter, on the bank of the South Fork of the American River, about 38 miles west of Rubicon Springs, when he spotted flacks of gold in the river. Exploration of the American River and its branches by prospectors began soon after and continued at a fever pace in the spring and summer of 1848. By the fall of 1848 a small mining camp, Fordís Bar, had been established on banks of the Middle Fork of the American River, about 10 miles down stream from the mouth of the Rubicon River. Prospectors worked all the branches of the American River and most likely include the Rubicon River in their search. For reasons of geology, (wrong kind of rock with very little gold or silver) the Rubicon River and its drainage were not meaningfully mined during the Gold Rush although most likely prospected and explored throughout its length. The lack of gold and silver may have something to do with the naming of the river. No mining claims were ever established at or near Rubicon Springs. By the 1870s, gold mining in the regions surrounding Rubicon Springs was subsiding and being replaced by ranching, logging and tourism.