The population of san francisco, california, skyrocketed around 1850 for which of the following reasons?

The answer is The Gold Rush brought treasure seekers, Silver discoveries, entrepreneurs of the banking industry, with the founding of Wells Fargo, development of the Port of San Francisco and the establishment in 1869 of overland access to the eastern U.S. rail system via the newly completed Pacific Railroad helped make the Bay Area a center for trade, immigrant laborers, as the population grew so did the businesses catering to the needs and tastes of the growing population.