The Northwest Seaport Alliance is a port authority based in the Puget Sound region of the United States, comprising the seaports of Seattle and Tacoma in Washington state. The combined port authority is the third largest cargo port in the United States and by container volume. The two seaports, which had been rivals for most of the 20th century but lost ground to nearby ports in British Columbia, proposed a merger of marine cargo operations in 2014. A public development authority was created in 2015 and approved by the Federal Maritime Commission, resulting in the formation of The Northwest Seaport Alliance on August 4, 2015. History Background In 1911, the Washington State Legislature authorized the creation of port districts through public referendums. The ports of Seattle and Tacoma were formed separately in 1911 and 1918, respectively, to establish public control of municipal waterfronts. The two ports, located apart, facilitated exports of the state's natural resources and imports from Asia, which intensified during World War I at the end of the decade. During World War II, the ports were used for military shipyards and other wartime uses, reverting to civilian trade afterwards. The rise of cargo containerization in the 1960s helped offset declining traffic to the Port of Seattle, leading to a $80 million modernization and expansion program begun in 1968. The Port of Tacoma debuted its own cargo container-ready facilities in 1970, and gradually lured away several large shipping lines from Seattle through the 1990s, including Alaska-based Totem Ocean Trailer Express (1976), SeaLand (1983), Maersk (1985), K Line (1988), and Evergreen Marine (1991). The Port of Seattle's largest line, Hyundai Merchant Marine, moved to a new, $65 million terminal in Tacoma in 1996. By the turn of the 21st century, Tacoma eclipsed Seattle to become the largest port in the state and 7th largest in the nation, but fell behind ports in Los Angeles and nearby Vancouver. In 2009, Seattle regained its title as the larger of the ports, but both suffered losses in overall cargo volume and revenue. Tacoma lost Maersk to Seattle after Maersk signed a vessel sharing agreement with CMA-CGM in 2009, but three years later attracted an alliance of three major international shippers from Seattle who had comprised 20 percent of cargo for the port. Merger proposals At a 1985 meeting of the Port Development Task Force of the Greater Seattle Chamber of Commerce, visiting Port