Where the Duwamish River flows into Elliott Bay, a flat stretch of shipyard, port terminals and warehouses sits on land that Seattle made for itself. Harbor Island, Washington is a man-made island, completed in 1909 and once the largest artificial island in the world. It is still a working industrial zone, so come to it as a chapter of city history rather than a place to spend a leisurely afternoon.
An Island Built From Seattle's Own Hills
Picture the steep ground of early downtown Seattle being moved and reshaped into brand new land. The Puget Sound Bridge and Dredging Company built the island from roughly 24 million cubic yards of material. Part of that earth came from the Jackson and Dearborn Street regrades, when the city flattened its hilly terrain, and the rest was dredged up from the Duwamish riverbed.
When it was finished, the island covered about 350 acres and held the world record for artificial islands until Treasure Island in San Francisco Bay took the title in 1938. Harbor Island kept growing to nearly 397 acres and won the record back in 1967. Much larger projects have since passed it, including Rokko Island in Kobe, Japan.