followed in the 1930s. Both crossings were later expanded to accommodate extra traffic: the Lincoln Tunnel in the 1940s and 1950s, and the George Washington Bridge in the 1960s. In 1955, the original Tappan Zee Bridge was built over one of the widest parts of the river, from Tarrytown to Nyack. The late 20th century saw a decline in industrial production in the Hudson Valley. In 1993, IBM closed two of its plants, in East Fishkill and Kingston, due to the company's loss of $16 billion over the previous three years. The plant in East Fishkill had 16,300 workers at its peak in 1984, and had opened in 1941 originally as part of the war effort. In 1996, the North Tarrytown plant of General Motors (GM) closed. In response to the plant closures, towns throughout the region sought to make the region attractive for technology companies. IBM maintained a mainframe unit at its Poughkeepsie plant, and newer housing and office developments were built near there as well. Commuting from Poughkeepsie to New York City also increased. Developers also looked to build on the property of the old GM plant. Around the time of the last factories' closing, environmental efforts to clean up the river progressed. For example, the Environmental Protection Agency (EPA) ordered General Electric (GE), which had polluted a 200-mile stretch of the river, to remove PCBs from the site of its old factory in Hudson Falls, as well as to remove millions of cubic yards of contaminated sediment from the river bottom. EPA's cleanup order was issued pursuant to the agency's designation of the polluted segment of the river as a Superfund site. Other conservation efforts also occurred, such as when Christopher Swain became the first person to swim all 315 miles of the Hudson River in support of cleaning it up. In conjunction with conservation efforts, the Hudson River region has seen an economic revitalization, especially in favor of green development. In 2009, the High Line was opened in the Chelsea neighborhood of Manhattan. This linear park has views of the river throughout its length. Also in 2009, the original Poughkeepsie railroad bridge, since abandoned, was converted into the Walkway Over the Hudson, a pedestrian park over the river. Emblematic of the increase in green development in the region, waterfront parks in cities like Kingston, Poughkeepsie, and Beacon were built, and several festivals are held annually. Landmarks