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History of the Design and Construction of the Bridge
The Golden Gate strait is a gap in a mountain range that was cut by an ancient river that passed through what was a dry valley until 10,000 years ago. That was when sea level was over 100 meters lower than today. The melting ice caused by the end of the last ice age raised the level of the sea, and the ocean slowly flowed back up the river canyon to form San Francisco Bay. Today, 60% of the rain and snow that falls on the State of California still drains through the Golden Gate.
The Golden Gate strait is the reason for the strong tides, frequent winds, fog, and salt air, all of which posed challenges for building a bridge across it. In addition, the infamous San Andreas Fault, cause of the 1906 San Francisco Earthquake, is only 7 miles (11 kilometers) offshore.
Native Americans lived around San Francisco Bay at least 4,000 years ago. Once Spanish explorers discovered the many natural resources of the area and the desirability of the Bay as a harbor, they established in 1776 a settlement called Yerba Buena, later re-named San Francisco.
In 1848, the population of the city was less than 500; in 1849, because of the Gold Rush, it was suddenly ten times greater. Shortly after 1900 the Bay Region’s population had reached a million. The major north-south highway in California, Highway 101, needed to span the Gate to become a viable statewide transportation artery.
In the early decades of the twentieth century, civil engineering made dramatic advances in the design and construction of long-span bridges. A great bridge across the Gate, an impossible vision before then, became a challenging possibility. Despite political opposition, scarce funds in the Great Depression that began in 1929, and the immense physical challenges of bridging a mile of water, the people of six counties in northern California voted to finance the Golden Gate Bridge. Engineers and construction workers with imagination, courage, and determination then came together to design and build what until then had been considered “the bridge that couldn’t be built.”
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