A little history from the excellent Oregon Encyclopedia article:
From 1927 to 1940, Swan Island was the site of Portland’s airport. Congress had allowed the Port of Portland to connect Swan Island to the mainland with fill so that a runway could be built. The fill for the runway and the addition of dredged material from the excavation of the main navigation channel increased the size of Swan Island by three times, to 900 acres. The Port completed the airstrip in time for a visit by Charles Lindbergh in September 1927. The increase in air traffic over the next decade necessitated a larger airport, and in 1940 the airport was moved to its current location in northeast Portland along the Columbia River.
During World War II, Swan Island was the site of one of the Kaiser shipyards and worker housing. At the request of the United States government, contractor and industrialist Henry J. Kaiser developed a major shipbuilding operation at Portland and across the Columbia at Vancouver, Washington. Between 1942 and 1945, the Kaiser shipyards produced 147 T-2 tankers at Swan Island, making it the Liberty and Victory ship capital of the United States. In all, 455 ships were produced at Kaiser’s Oregon shipyards during World War II. The temporary worker housing created on Swan Island during the war was used to accommodate some of the people displaced by the Vanport flood in 1948. Many of the displaced had to remain for up to a year at Swan Island because of the post-war housing shortage in Portland.
After World War II, Swan Island became the center for Port of Portland operations, including the dry dock and ship repair facilities. Since Swan Island is centrally located in Portland’s harbor, many industrial operations have developed there, especially for distribution, warehousing, and manufacturing activities.