The Golden Gate Bridge, at the time the world's longest suspension bridge by span, opened between San Francisco and Marin County, California.

The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the one-mile-wide (1.6 km) strait connecting San Francisco Bay and the Pacific Ocean in California, United States. The structure links San Francisco—the northern tip of the San Francisco Peninsula—to Marin County, carrying both U.S. Route 101 and California State Route 1 across the strait. It also carries pedestrian and bicycle traffic, and is designated as part of U.S. Bicycle Route 95. Recognized by the American Society of Civil Engineers as one of the Wonders of the Modern World, the bridge is one of the most internationally recognized symbols of San Francisco and California.

The world's longest suspension bridges are listed according to the length of their main span. The length of the main span is the most common method of comparing the sizes of suspension bridges, often correlating with the height of the towers and the engineering complexity involved in designing and constructing the bridge. If one bridge has a longer span than another, it does not necessarily mean that the bridge is longer from shore to shore.

San Francisco, officially the City and County of San Francisco, is a commercial, financial, and cultural center of Northern California. With a population of 827,526 residents as of 2024, San Francisco is the fourth-most populous city in the U.S. state of California and the 17th-most populous in the United States. San Francisco has a land area of 46.9 square miles at the upper end of the San Francisco Peninsula and is the fifth-most densely populated U.S. county. Among U.S. cities proper with over 250,000 residents, San Francisco is ranked first by per capita income and sixth by aggregate income as of 2023. San Francisco anchors the 13th-most populous metropolitan statistical area in the U.S., with almost 4.6 million residents in 2023. The larger San Jose–San Francisco–Oakland combined statistical area, the fifth-largest urban region in the U.S., had a 2023 estimated population of over nine million.