Editing Hudson River (section)

===20th and 21st centuries===
[[File:George Washington Bridge from New Jersey-edit.jpg|thumb|The [[George Washington Bridge]] links [[Upper Manhattan]] and [[Fort Lee, New Jersey]]]]
Starting in the 20th century, the technological requirements needed to build large crossings across the river were met. This was especially important by New York City, as the river is fairly wide at that point. In 1927, the [[Holland Tunnel]] opened between New Jersey and [[Lower Manhattan]]. The tunnel was the longest underwater tunnel in the world at the time, and used an advanced system to ventilate the tunnels and prevent the build-up of carbon monoxide.<ref name="NYC Crossings"/><ref name="Holland Tunnel"/> The original upper level of the [[George Washington Bridge]] and the first tube of the [[Lincoln Tunnel]] 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.<ref name="PANYNJ"/> In 1955, the original [[Tappan Zee Bridge (1955–2017)|Tappan Zee Bridge]] was built over [[Tappan Zee|one of the widest parts of the river]], from [[Tarrytown, New York|Tarrytown]] to [[Nyack, New York|Nyack]].<ref name="Old Tapppan Zee Bridge"/><ref name="Old and New Tappan Zee Bridge"/><ref name="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, New York|East Fishkill]] and [[Kingston, New York|Kingston]], due to the company's loss of $16&nbsp;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.<ref name="IBM"/> In 1996, the North Tarrytown plant of [[General Motors]] (GM) closed.<ref name="NT GM Plant closes"/> In response to the plant closures, towns throughout the region sought to make the region attractive for technology companies. IBM maintained a [[mainframe computer|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.<ref name="IBM"/> Developers also looked to build on the property of the old GM plant.<ref name="NT GM Plant closes"/>

[[File:Mid-Hudson balloon festival 14.JPG|thumb|left|The Hudson Valley Hot-Air Balloon Festival, 2009|alt=The 2009 Mid-Hudson balloon festival]]
[[File: US Airways Flight 1549 (N106US) after crashing into the Hudson River (crop 2).jpg|thumb|right| [[US Airways Flight 1549]] after landing on the waters of the Hudson River in January 2009]]

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 [[Polychlorinated biphenyl|PCBs]] from the site of its old factory in [[Hudson Falls, New York|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.<ref name="EPA-hudson cleanup"/> 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.<ref name="AutoYG-3"/>

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 (Manhattan)|Chelsea neighborhood]] of Manhattan. This linear park has views of the river throughout its length.<ref name="High Line National Geographic"/> Also in 2009, the original Poughkeepsie railroad bridge, since abandoned, was converted into the [[Walkway Over the Hudson]], a pedestrian park over the river.<ref name="Walkway Timeline"/> Emblematic of the increase in green development in the region, waterfront parks in cities like Kingston, Poughkeepsie, and [[Beacon, New York|Beacon]] were built, and several festivals are held annually.<ref name="Hudson Valley revitalization"/>