Bridge Facts

Before the Bridge | During Construction | After Construction

Ocean tides flow through the Golden Gate four times a day -- twice coming in and twice going out. The quantity of salt water in motion between high and low tides averages 390 billion gallons.

Water depth at the Golden Gate is more than 300 feet, but San Francisco Bay waters are, on average, just 14 feet deep.

Thousands of animal species, including over 130 species of fish, call the bay home. Four distinct runs of Chinook salmon migrate through the bay on their way to spawn upstream.

San Francisco Bay is a drowned valley. At the end of the most recent Ice Age, 10,000 years ago, melting ice caused rising ocean levels. Water crept steadily through the Golden Gate and flooded the land beyond.

In October 1933, Civilian Conservation Corps workers arrived at Muir Woods National Monument, a protected old-growth redwood forest on the Marin headlands. They built revetments, bridges, buildings, benches, and an amphitheater -- anticipating a surge of new visitors to the majestic forest after the bridge opened.