Rising from a tidal mudflat at the mouth of the Los Angeles River, the Port of Long Beach has grown through the 20th century into the one of the busiest deepwater ports. The ultramodern Port of Long Beach, the second-largest active harbor in the United States in the first decade of the 21st century, progressed steadily through a difficult adolescence fueled by the ambitions of a visionary few local community leaders who overcame political opposition to create a port separate and distinct from its neighboring Port of Los Angeles. Fueled by oil, Southern California's unprecedented post-World War II growth, and the container revolution, the Port of Long Beach surmounted numerous natural and man-made hurdles to position itself, in its own right, as a critical link in the nation's global supply chain.