The Delaware River was named for "Lord De La Warr" (Thomas West, b. 1577, d. 1618), first colonial governor of Virginia.
A river basin or watershed is the area of land that supplies water to a river and its tributaries. The Delaware River Basin contains 12,755 square miles, draining parts of Pennsylvania, New Jersey, New York, and Delaware. Pennsylvania contains 6,422 square miles, or 50.3% of the basin's total land area; New Jersey contributes 2,969 square miles, or 23.3%; 2,362 square miles, or 18.5% is in New York; and the river's namesake, Delaware, contains only 1,002 square miles, or 7.9% of the river's drainage area. The river flows through two major geological formations: the Delaware Water Gap, and the Trenton Fall Line.
Headwaters to the Bay
The headwaters of the Delaware are in New York's Catskill Mountains. The west branch of the river (also referred to as the Mohawk branch) rises in Schoharie County, New York. The east branch rises in the Town of Roxbury, Delaware County, New York. The confluence is just south of the Village of Hancock, also in Delaware County NY. The trip from the Catskill Mountains to the Atlantic Ocean covers approximately 280 miles.
DVRPC History 
For much of the first half of the 17th century, the center of European colonization along the River was focused in present-day Delaware County. In the 1640s, the Swedish governor for the region, Johan Printz, established the first European capital in Pennsylvania in what is now known as Tinicum Township. From this location, European settlements spread up and down the river, most prominently at Marcus Hook, Chester, and Tinicum. Between these early centers of commerce and culture, colonists established farms and traded with the local Native Americans as the regional governing authority moved from the Swedish, to the Dutch, to the English, and finally to the Americans.
In Philadelphia, as in Delaware County, much of the city’s historical development grew along the waterfront owing to the importance of the river for trade, transportation, and communication. In the decades following the Declaration of Independence, the waterfront developed rapidly to the north and south of the original 17th-century settlement with industrial factories, warehouses, port facilities, and residential neighborhoods. To the south, industrial wharves were constructed to provide more area for port operations. Several of these wharves became entry points for successive waves of immigrants throughout the 1800s, resulting in neighborhoods in the surrounding area of African American, Irish, Italian, and Lebanese immigrants.
From the time the first European settlements in the area were established in 1624–1625 until the middle of the 19th century, the Bucks County waterfront area was mostly rural farmland with the occasional riverfront town or mansion used as a summer retreat by prominent regional families. Due to its location between Philadelphia and New York, it also served as a transportation route between Philadelphia and New York. The King’s Highway was constructed in 1686, the first bridge across the river at Morrisville was constructed in 1804, and train tracks were laid along the route in 1834.
Henry Hudson, an Englishman in the service of the Dutch East-India company, discovered the Delaware bay the 28th of August, 1609, but he made no attempt to ascend the river. The Delaware had a multiplicity of names. The Indians called it Marisqueton, Mackeriskitton and Makerishkiskon, Lenapa, Wihittuck, or, the stream of the Lenape. It was called Zuydt or South River by the Dutch; also, Nassau, Prince Hendrick's and Charles River. The Swedes called it New Swedeland stream, while to the English it was generally known as the Delaware. The Dutch less frequently called it New River, and some Indians called it Pautaxa.
Captain Cornelius Jacobson May ascended the river some distance in 1614, and two years afterwards Captain Hendrickson discovered the Schuylkill. For a number of years the history of the country of watered by the Delaware is a relation of the feeble struggles of Holland, Sweden and England for empire on its banks. It was about this period that Bucks County was first traveled by Europeans. In 1616 three Dutch traders set out from Fort Nassua, now Albany, to explore the interior; they struck across the headwaters of the Delaware, down which they traveled to the Schuylkill.
There is only a brief record of Hollanders planting settlements along the Delaware. They and the French carried on a profitable trade with the Indians as early as 1621, and no doubt now and then one of them pushed his way further from the shores to trap and trade. In 1623 the Dutch West-India company erected a fort where Gloucester New Jersey now stands; but affairs were so unpromising on the Delaware that it was abandoned in 1630.
No fewer than 4-dozen historic cities and towns border the river. From cosmopolitan Philadelphia to quiet little Deposit Village, the riverside is rich in "living places," – all styles, all prices, all accommodating.