[3] Its watershed drains an area of 13,539 square miles (35,070 km2) and provides drinking water for 17 million people, including half of New York City via the Delaware Aqueduct.

Hudson, an English navigator, was hired to find a western route to Cathay (China), but his encounters set the stage for Dutch colonization of North America in the 17th century.

[6] The name of the barony (later an earldom) is pronounced as in the current spelling form "Delaware" (/ˈdɛləwɛər/ ⓘ DEL-ə-wair)[9] and is thought to derive from French de la Guerre.

It has often been reported that the river and bay received the name "Delaware" after English forces under Richard Nicolls expelled the Dutch and took control of the New Netherland colony in 1664.

[17]: vi, 9  The waters of the Delaware River's basin are used to sustain "fishing, transportation, power, cooling, recreation, and other industrial and residential purposes.

The West Branch rises in Schoharie County, New York at 1,886 feet (575 m) above sea level, near Mount Jefferson, and flows tortuously through the plateau in a deep trough.

The river flows down a broad Appalachian valley, passing Hawk's Nest overlook on the Upper Delaware Scenic Byway.

The river flows southeast for 78 miles through rural regions along the New York-Pennsylvania border to Port Jervis and Shawangunk Ridge.

At this point, the Walpack Ridge deflects the Delaware into the Minisink Valley, where it follows the southwest strike of the eroded Marcellus Formation beds along the Pennsylvania–New Jersey state line for 25 miles (40 km) to the end of the ridge at Walpack Bend in the Delaware Water Gap National Recreation Area.

At the time of the arrival of the Europeans in the early 17th century, the area near the Delaware River was inhabited by the Native American Lenape people.

Beginning in 1664, the region became an English possession as settlement by Quakers established the colonies of Pennsylvania (including present-day Delaware) and West Jersey.

In the eighteenth century, cities like Philadelphia, Camden (then Cooper's Ferry), Trenton, Wilmington and New Castle were established upon the Delaware and their continued commercial success into the present day has been dependent on access to the river for trade and power.

The river provided the path for the settlement of northeastern Pennsylvania's Lehigh Valley, and northwestern New Jersey by German Palatine immigrants—a population that became key in the agricultural development of the region.

This settlement marked one of the earliest European establishments in the region, with Fort Christina (located near modern-day Wilmington, Delaware) becoming a key trading post and symbol of Swedish colonial ambition.

New Sweden became a center for trade and cultural exchange between the Swedish settlers, Native Americans, and neighboring Dutch colonies.

The fort and surrounding settlements played a crucial role in the early European rivalry for control of North America's resources and territory.

This era of Swedish colonization is an important part of the Delaware River's history, adding to its diverse cultural legacy.

To this end, the Battle of Red Bank and the Siege of Fort Mifflin were fought on and along the shores of the Delaware by the American and British navies, commanded by Commodore John Hazelwood and Admiral Francis Reynolds respectively.

Because of massive environmental opposition, dwindling funds, and an unacceptable geological assessment of the dam's safety, the government transferred the property to the National Park Service in 1978.

The National Park Service found itself as the caretaker of the previously endangered territory, and with the help of the federal government and surrounding communities, developed recreational facilities and worked to preserve the remaining historical structures.

[32] In 1984, the U.S. Department of the Treasury authorized the creation of a wine region or "American Viticultural Area" called the Central Delaware Valley AVA located in southeastern Pennsylvania and New Jersey.

The wine appellation includes 96,000 acres (38,850 ha) surrounding the Delaware River north of Philadelphia and Trenton, New Jersey.

[34][35] In the Project of 1885, the U.S. government undertook systematically the formation of a 26-foot (7.9 m) channel 600 feet (180 m) wide from Philadelphia to deep water in Delaware Bay.

There is an effort underway to deepen the 102.5-mile stretch of this federal navigation channel, from Philadelphia and Camden to the mouth of the Delaware Bay to 45 feet.

In 2015, the ports of Philadelphia, Camden, and Wilmington handled 100 million tons of cargo from 2,243 ship arrivals, and supported 135,000 direct or indirect jobs.

As of 2011, crude oil was the largest single commodity transported on the Delaware River, accounting for half of all annual cargo tonnage.

The two sides eventually took their case to the U.S. Supreme Court, and in 1931, New York City was allowed to draw 440 million US gallons (1,700,000 m3) of water a day from the Delaware and its upstream tributaries.

[50] The activist groups claim that there is about 7–10 million pounds of toxic chemicals flowing through the waterways due to dumping by DuPont Chambers Works.

In March 2023, a pipe rupture at a Trinseo chemical plant in Bristol, Pennsylvania, released over 8,000 gallons of latex finishing material into the Otter Creek tributary, leading to a water advisory in Philadelphia.

The local governments have worked in association with FEMA to address many of these problems, however, due to insufficient federal funds, progress is slow.