New floating bridge opens in Seattle; I-90 stretches from coast to coast

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The rebuilt Lacey V. Murrow Bridge over Lake Washington opens in Seattle. The new bridge, which was actually the eastbound lanes of Interstate 90 (the westbound lanes cross the lake on a separate bridge), connects the city and its eastern suburbs. It replaced the original Murrow Bridge, the first floating concrete bridge in the world, which was destroyed by a flood in November 1990.

In December 1938, Washington governor Clarence Martin and Lacey V. Murrow, the director of the Washington Toll Bridge Authority, broke ground on what would be the largest floating structure in the world: the Lake Washington Floating Bridge, also known as the Mercer Island Bridge, between Seattle to the west and Bellevue, Washington, to the east. (It was renamed for Murrow in 1967.) At the time the bridge was built, it carried US Route 10 across the lake; a few decades later, that highway became Interstate 90. The bridge was a Public Works Administration-financed project designed to give work to unemployed Washingtonians and to make the towns across the lake from Seattle more accessible to suburban development.

When the bridge opened in 1940, the Seattle Times called it “the biggest thing afloat.” It was almost two miles long, contained 100,000 tons of steel, floated on more than 20 hollow concrete pontoons, and carried 5,000 cars each day. (By 1989, its daily load was closer to 100,000 cars.)

In 1990, while the bridge was closed for repairs, construction workers punched giant holes in the pontoons that kept it afloat and went home for the weekend. A few days of rain and high winds filled the pontoons with water, and the bridge broke apart and sank.


Repairing it was no easy task: The sinking pontoons had pulled more than a half-mile of highway into the lake with them, and the structure needed to be rebuilt from scratch. This project took three years and cost $93 million. When the bridge finally reopened, it closed one of the last remaining gaps in the interstate highway system: a person could drive from Boston to Seattle without ever leaving I-90.