Final answer:
Oakland is the city that lies directly across the bay from San Francisco. It is a significant urban center in the San Francisco Bay Area and, like San Francisco, has contributed to the Bay Area's dynamic growth and diverse economy.
Step-by-step explanation:
The city that lies directly across the bay from San Francisco is Oakland. Oakland is positioned on the eastern side of the San Francisco Bay and is among the top 50 in population in the United States. Like San Francisco, which is renowned for its historical significance and its strategic military location of El Presidio Real de San Francisco, Oakland has developed into a significant urban center with strong economic ties to the Bay Area. The Bay Area itself is integral to California’s diverse and rich economy, playing a substantial role in sectors like the high-tech industry in Silicon Valley and foreign trade through the port of Los Angeles. The rapid development of cities like San Francisco during the Gold Rush era, which saw San Francisco’s population skyrocket, similarly accelerated the growth of its neighboring cities, including Oakland.