In Tacoma, Washington, the original Tacoma Narrows Bridge collapses in a windstorm, a mere four months after the bridge's completion.
The 1940 Tacoma Narrows Bridge, the first Tacoma Narrows Bridge, was a suspension bridge in the U.S. state of Washington that spanned the Tacoma Narrows strait of Puget Sound between Tacoma and the Kitsap Peninsula. It opened to traffic on July 1, 1940, and dramatically collapsed into Puget Sound on November 7 of the same year. The bridge's collapse has been described as "spectacular" and in subsequent decades "has attracted the attention of engineers, physicists, and mathematicians". Throughout its short existence, it was the world's third-longest suspension bridge by main span, behind the Golden Gate Bridge and the George Washington Bridge.
Construction began in September 1938. From the time the deck was built, it began to move vertically in windy conditions, so construction workers nicknamed the bridge Galloping Gertie. The motion continued after the bridge opened to the public, despite several damping measures. The bridge's main span finally collapsed in 40-mile-per-hour (64 km/h) winds on the morning of November 7, 1940, as the deck oscillated in an alternating twisting motion that gradually increased in amplitude until the deck tore apart.
The portions of the bridge still standing after the collapse, including the towers and cables, were dismantled and sold as scrap metal. Efforts to replace the bridge were delayed by the United States' entry into World War II, but in 1950, a new Tacoma Narrows Bridge opened in the same location, using the original bridge's tower pedestals and cable anchorages. The portion of the bridge that fell into the water now serves as an artificial reef.
The bridge's collapse had a lasting effect on science and engineering. In many physics textbooks, the event is presented as an example of elementary forced mechanical resonance, but it was more complicated in reality; the bridge collapsed because moderate winds produced aeroelastic flutter that was self-exciting and unbounded: For any constant sustained wind speed above about 35 mph (56 km/h), the amplitude of the (torsional) flutter oscillation would continuously increase, with a negative damping factor, i.e., a reinforcing effect, opposite to damping. The collapse boosted research into bridge aerodynamics-aeroelastics, which has influenced the designs of all later long-span bridges.
Tacoma ( tə-KOH-mə) is the county seat of Pierce County, Washington, United States. A port city, it is situated along Washington's Puget Sound, 32 miles (51 km) southwest of Seattle, 31 miles (50 km) northeast of the state capital, Olympia, and 58 miles (93 km) northwest of Mount Rainier National Park. The population was 219,346, according to the 2020 census. Tacoma is the second-largest city in the Puget Sound area and the third-largest in the state. Tacoma also serves as the center of business activity for the South Sound region, which has a population of about 1 million.
Tacoma adopted its name after the nearby Mount Rainier, originally and locally called Takhoma or Tahoma. It is locally known as the "City of Destiny" because the area was chosen to be the western terminus of the Northern Pacific Railroad in the late 19th century. The decision of the railroad was influenced by Tacoma's neighboring deep-water harbor, Commencement Bay. By connecting the bay with the railroad, Tacoma's motto became "When rails meet sails". Commencement Bay serves the Port of Tacoma, a center of international trade on the Pacific Coast and Washington's largest port. The city gained notoriety in 1940 for the collapse of the Tacoma Narrows Bridge, which earned the nickname "Galloping Gertie".
Like most industrial cities, Tacoma suffered a prolonged decline in the mid-20th century as a result of suburbanization and divestment. Since the 1990s, downtown Tacoma has experienced a period of revitalization. Developments in the downtown include the University of Washington Tacoma; Line T (formerly Tacoma Link), the first modern electric light rail service in the state; the state's highest density of art and history museums; and a restored urban waterfront, the Thea Foss Waterway.