The Hudson River is one of the most important and historically significant rivers in the northeastern United States. Flowing primarily through eastern New York State, the river stretches for about 315 miles (507 km) from the Adirondack Mountains to the Atlantic Ocean at New York Harbor. It has played a major role in the exploration, settlement, transportation, trade, and economic development of the region for centuries.
Named after English explorer Henry Hudson, who sailed up the river in 1609 while searching for a route to Asia, the Hudson River later became a vital waterway connecting inland regions with the Atlantic coast. During the colonial era and the American Revolution, it held immense strategic importance and helped shape the history of the United States.
The river is also famous for its stunning natural scenery, especially through the Hudson Valley, where forested hills, cliffs, historic towns, vineyards, and castles line its banks. Today, the Hudson River supports major cities including Albany and New York City, while also serving as an important ecological corridor for fish, birds, and other wildlife.
Table of Contents
Origin and Source of the Hudson River
The Hudson River originates in the Adirondack Mountains of northern New York State. Its generally recognized source is Lake Tear of the Clouds, a small glacial lake located on the slopes of Mount Marcy, the highest peak in New York. The lake lies within the Adirondack High Peaks region at an elevation of about 4,322 feet (1,317 meters) above sea level.
From Lake Tear of the Clouds, a small stream known as Feldspar Brook flows into the Opalescent River, which later joins the upper Hudson River. In its early course, the river flows southward through dense forests, rocky valleys, and mountainous terrain before gradually widening as it moves toward central and eastern New York.
The upper Hudson River is primarily fed by snowmelt, rainfall, mountain streams, and numerous small tributaries originating in the Adirondack region. This mountainous source area provides cold, clean freshwater that supports diverse aquatic ecosystems and helps maintain the river’s flow throughout the year.
Course of the Hudson River
The Hudson River is a 315-mile river flowing through eastern New York State in the northeastern United States. It begins in the Adirondack Mountains at Lake Tear of the Clouds and flows generally southward before emptying into the Atlantic Ocean at New York Harbor. In its lower section, the river also forms part of the boundary between New York and New Jersey.
The course of the Hudson River is commonly divided into three major geographic sections: the Upper Course, the Middle Course, and the Lower Course.
1. Upper Course (Headwaters)
The Hudson River originates near Mount Marcy in the Adirondack Mountains, where a small stream flows out of Lake Tear of the Clouds. In this upper section, the river begins as a narrow, fast-flowing trout stream moving through rugged mountain terrain, forests, and rocky valleys.
From its source, the river follows a winding southeastward path through the Adirondack region toward Corinth. It then bends northeastward near Hudson Falls before eventually turning south at the Federal Dam in Troy. This upper section contains rapids, waterfalls, and steep gradients typical of a youthful mountain river.
One of the most important tributaries of the Hudson River is the Mohawk River, which joins the Hudson just north of Albany. The Mohawk River significantly increases the Hudson’s water volume and historically provided an important transportation route connecting the Atlantic coast with the interior of North America.
2. Middle Course (Hudson Valley)
Below Troy, the Hudson River enters its middle course and flows almost entirely southward for nearly 200 miles through the scenic Hudson River Valley. This region is one of the most famous landscapes in New York State and has played an important role in American history, art, agriculture, and trade.
In this section, the river flows between the Catskill Mountains to the west and the Taconic Mountains to the east. Farther south, the river cuts through the dramatic Hudson Highlands, a rugged extension of the Appalachian Mountain system known for its steep hills, cliffs, and scenic beauty.
A defining feature of the middle and lower Hudson is its tidal nature. Due to the influence of the Atlantic Ocean, tides affect the river as far north as Troy. Because of this, the lower Hudson functions as a tidal estuary or “drowned river,” where water levels and currents regularly rise and fall with ocean tides. Historically, Native American communities referred to it as the “river that flows both ways” because the tidal currents could reverse the river’s direction temporarily.
3. Lower Course (New York Harbor and Estuary)
South of the Hudson Highlands, the river broadens considerably and enters its lower course. In this section, the Hudson forms the boundary between New York and New Jersey and becomes heavily urbanized as it approaches the New York metropolitan area.
The river passes alongside the famous Palisades, a line of steep basalt cliffs rising dramatically above the western bank of the river. These geological formations are among the most recognizable natural landmarks in the region.
Farther south, the Hudson flows past Manhattan and Jersey City before entering New York Harbor. The river ultimately empties into the Atlantic Ocean through The Narrows, the narrow maritime passage connecting Upper and Lower New York Bay. This final section of the Hudson is one of the busiest and most economically important waterways in the United States.
Hudson River Estuary
The Hudson River Estuary is a 153-mile-long tidal estuary extending from the Federal Dam at Troy to Verrazzano-Narrows in New York City. It forms the lower portion of the Hudson River and is one of the largest freshwater tidal estuaries in the United States. Influenced by tides from the Atlantic Ocean, the estuary contains a constantly changing mixture of freshwater flowing from the north and saltwater moving inland from the ocean, creating a rich and highly productive aquatic ecosystem.
One of the most unique characteristics of the Hudson River Estuary is its strong tidal influence. Because the river drops only about five feet in elevation between Troy and the Atlantic Ocean, ocean tides travel all the way upstream to Troy. This causes the river’s water levels and currents to rise, fall, and even reverse direction twice each day. The Lenape people historically called the river Muhheakantuck or Mahicannituk, meaning “the waters that are never still” or “the river that flows both ways,” reflecting this unusual tidal behavior.
The boundary between freshwater and saltwater, known as the salt front, constantly shifts depending on rainfall, seasonal river flow, and drought conditions. In most years, this mixing zone lies between Yonkers and Newburgh. The estuary also contains extensive freshwater tidal marshes, mudflats, wetlands, and shallow bays that provide critical ecological functions such as water filtration, flood control, and shoreline stabilization.
The Hudson River Estuary supports exceptional biodiversity and serves as an important habitat for more than 200 fish species and many migratory birds. It is especially important as a spawning and nursery ground for fish such as striped bass, Atlantic sturgeon, American shad, and river herring. Wetlands and shoreline habitats along the estuary also form part of the Atlantic Flyway, making the region vital for seasonal bird migration.
Conservation and scientific research play a major role in protecting the estuary. The Hudson River National Estuarine Research Reserve manages protected areas including Piermont Marsh, Iona Island, Tivoli Bays, and Stockport Flats. These sites are used for environmental monitoring, habitat restoration, scientific research, and educational programs. The New York State Department of Environmental Conservation also operates the Hudson River Estuary Program, which works with regional partners to improve water quality, restore ecosystems, and support long-term watershed management.
The estuary is deeply connected to surrounding communities and provides numerous opportunities for boating, fishing, kayaking, hiking, and wildlife observation. Parks, waterfront trails, and greenways along the river attract millions of visitors each year while also supporting tourism and recreation. Today, the Hudson River Estuary remains one of the most important natural and cultural landscapes in the northeastern United States, balancing ecological conservation with urban development and human activity.
Hudson River Basin
The Hudson River Basin is the large watershed area drained by the Hudson River and its numerous tributaries. The basin stretches across much of eastern and central New York and also includes parts of Vermont, Massachusetts, Connecticut, and New Jersey. It contains a wide variety of landscapes, including the Adirondack Mountains, fertile valleys, forests, wetlands, lakes, and densely populated urban regions. The river system supports millions of people through water supply, agriculture, transportation, recreation, and industry.
According to the United States Geological Survey, the Hudson River Basin is commonly divided into three major sections based on geography and hydrological characteristics: the Upper Hudson River Basin, the Mohawk River Basin, and the Lower Hudson River Basin.
1. Upper Hudson River Basin
The Upper Hudson River Basin extends from the headwaters in the Adirondack Mountains southward to Troy. This northern region drains around 4,590 square miles and is dominated by forests, mountain lakes, rocky terrain, and wilderness areas located largely within Adirondack Park.
The Hudson River begins near Mount Marcy at Lake Tear of the Clouds, where a small stream known as Feldspar Brook joins the Opalescent River before forming the main river channel. In this upper course, the river descends more than 4,000 feet, creating swift currents, rapids, and waterfalls. The water in this section is cold, clear, and fast-moving, supporting healthy freshwater ecosystems.
The Upper Hudson Basin also contains 14 major dams that are used for hydroelectric power generation, flood control, and navigation management. These dams help regulate river flow and support regional infrastructure throughout eastern New York.
Several major tributaries feed the upper basin. The Sacandaga River is one of the largest tributaries and is controlled by the Conklingville Dam, which created Great Sacandaga Lake. The Schroon River drains northeastern Adirondack lakes and forests before joining the Hudson near Warrensburg. Other important tributaries include the Batten Kill and the Hoosic River, which originate in Vermont and Massachusetts.
2. Mohawk River Basin
The Mohawk River Basin forms the largest tributary system of the Hudson River and is often considered the western branch of the basin. The Mohawk River drains approximately 3,460 square miles of central New York before joining the Hudson near Cohoes.
This basin occupies a broad valley that cuts through the Appalachian Mountain system, creating one of the few natural east-west transportation corridors in the northeastern United States. Because of this strategic location, the valley became the route for the historic Erie Canal, which connected the Hudson River to the Great Lakes and played a major role in the economic growth of New York State.
The Mohawk Basin includes fertile agricultural land, historic canal towns, industrial cities, and rolling uplands. Major tributaries feeding the Mohawk River include the West Canada Creek and East Canada Creek, which bring cold freshwater from the southern Adirondacks. The Schoharie Creek drains the northern slopes of the Catskill Mountains before entering the Mohawk River. Smaller tributaries such as Oriskany Creek and Sauquoit Creek drain farmland and rural valleys across central New York.
3. Lower Hudson River Basin
The Lower Hudson River Basin stretches from Troy southward to New York Harbor and includes the tidal estuary section of the river. Unlike the upper river, this section lies close to sea level and is heavily influenced by Atlantic Ocean tides. As a result, water levels and currents change throughout the day, and in some areas the river can temporarily flow in both directions depending on tidal movement.
This section of the basin is surrounded by the Catskill Mountains to the west and the Hudson Highlands farther south. The region contains tidal wetlands, marshes, mudflats, urban waterfronts, and highly developed transportation corridors.
The northern part of the Lower Hudson Basin, extending from Troy to Wappingers Falls, remains entirely freshwater despite the tidal influence. Major tributaries in this section include the Fishkill Creek, Rondout Creek, and Wallkill River. Farther south, the river gradually becomes brackish as saltwater from the Atlantic mixes with freshwater from upstream. In this lower estuarine zone, important tributaries include the Croton River, which is an important part of New York City’s water supply system, and the Sparkill Creek.
The Hudson River Basin as a whole is an ecologically and economically important region that supports transportation, fisheries, agriculture, hydroelectric power, recreation, and millions of residents throughout the northeastern United States.
Tributaries of the Hudson River
The Hudson River is fed by a large network of rivers, creeks, streams, and watersheds throughout its 315-mile course from the Adirondack Mountains to New York Harbor. The river system contains more than 30 named tributaries, many of which originate in the Adirondack Mountains, Catskill Mountains, Taconic Range, and surrounding valleys. These tributaries supply freshwater, sediment, nutrients, and ecological diversity to the Hudson River Basin.
Tributaries of the Hudson are commonly classified according to the side of the river from which they enter — either the western (right-bank) side or the eastern (left-bank) side.
Right-Bank Tributaries (Western Side) of the Hudson River
The western side of the Hudson River receives water from several major tributaries flowing from the Adirondacks, Catskills, and western valleys of New York.
Mohawk River
The Mohawk River is the largest tributary of the Hudson River and one of the most historically important rivers in New York State. Stretching about 149 miles, it flows eastward across central New York before joining the Hudson near Cohoes. The Mohawk Valley forms a natural transportation corridor through the Appalachian Mountains and later became the route of the historic Erie Canal.
Sacandaga River
The Sacandaga River is a 64-mile-long tributary of the Hudson River located in the southern Adirondack Mountains of upstate New York. It flows southeasterly before being impounded by the Conklingville Dam, creating the 29-mile-long Great Sacandaga Lake. Below the dam, the river resumes its course for a short stretch before flowing into the Hudson River at Hadley.
Wallkill River
The Wallkill River is an 88.3-mile-long tributary of the Hudson River that flows generally northward from northern New Jersey into New York. Unique for its northward flow, it begins at Lake Mohawk in Sparta Township, NJ, and ultimately empties into Rondout Creek in New York to reach the Hudson River.
Esopus Creek
Esopus Creek is a 65.4-mile tributary in New York’s Catskill Mountains, flowing from Winnisook Lake to the Hudson River. It is famously divided by the Ashokan Reservoir into the trout-rich Upper Esopus and the lower warmwater section, serving as a major NYC water source and outdoor recreation hub.
Rondout Creek
Rondout Creek is a 63.3-mile-long tributary of the Hudson River in New York’s Ulster and Sullivan counties. Originating in the Catskill Mountains, it flows southeast through Ellenville, turns northeast over High Falls, and empties into the Hudson River at Kingston, famously passing the historic Rondout Lighthouse.
Left-Bank Tributaries (Eastern Side) of the Hudson River
The eastern side of the Hudson River receives tributaries flowing from the Taconic Mountains, Vermont highlands, and eastern valleys of New York and Massachusetts.
Croton River
The Croton River is a 40-km waterway in southern New York that flows into the Hudson River. Fed by three main tributaries, it forms a vital part of the New York City water supply system via the New Croton Reservoir and Gorge. The river is formed in Croton Falls where the East and West Branch tributaries meet, meandering through northern Westchester County before draining into the Hudson River.
Hoosic River
The Hoosic River is a 76-mile-long tributary of the Hudson River that flows northwestward from the Berkshires in Massachusetts, briefly into southern Vermont, and across eastern New York. It empties into the Hudson River about 15 miles north of Troy, near Stillwater. Known for its scenic valleys, varied recreational paddling, and flood-control infrastructure, it serves as a prominent waterway for both outdoor enthusiasts and local communities.
Batten Kill
The Batten Kill (or Battenkill River) is a scenic 59.4-mile-long river that flows from its source in East Dorset, Vermont, southwest into New York, where it eventually empties into the Hudson River. It is celebrated for its world-class trout fishing and recreational activities like tubing and kayaking.
Schroon River
The Schroon River is a 67.7-mile-long recreational tributary of the Hudson River located entirely within the Adirondack Park in upstate New York. Flowing from Underwood to Warrensburg, it is highly regarded for kayaking, premier trout fishing, and scenic Adirondack camping.
Kinderhook Creek
Kinderhook Creek is a scenic, 49-mile-long tributary in upstate New York that flows from the Taconic Mountains in Massachusetts down to the Hudson River. It is highly regarded for its thriving brown trout fishery, peaceful hiking trails, and stunning autumn foliage.
Frequently Asked Questions about Hudson River
Where is the Hudson River?
The Hudson River is located in eastern New York State in the northeastern United States. It flows south from the Adirondack Mountains through the Hudson Valley and forms part of the border between New York and New Jersey before emptying into New York Harbor and the Atlantic Ocean.
Where does the Hudson River start and end?
The Hudson River begins at Lake Tear of the Clouds in the Adirondack Mountains near Mount Marcy. It flows south for about 315 miles before ending at New York Harbor, where its waters enter the Atlantic Ocean through The Narrows.
How long is the Hudson River?
The Hudson River is approximately 315 miles (507 kilometers) long from its source in the Adirondack Mountains to its mouth at New York Harbor.
How deep is the Hudson River?
The Hudson River has an average depth of about 30 feet (9.1 meters), although its depth varies greatly along different sections of the river. In many places, the river ranges between 30 and 200 feet deep. The deepest known section, called “World’s End,” near West Point, reaches depths of about 200 feet.
How deep is the Hudson River in NYC?
In the immediate New York City area, the Hudson River has a maintained commercial shipping channel depth ranging from approximately 40 to 48 feet. While the average depth of the Hudson estuary is around 30 feet, actual depths vary considerably depending on the location, tidal conditions, and navigation channels used by large commercial vessels.
Can you swim in the Hudson River?
Yes, swimming is allowed in certain parts of the Hudson River, especially during organized events or at designated riverfront parks and beaches. However, swimming conditions vary depending on water quality, tides, currents, and local regulations.
Is it safe to swim in the Hudson River?
Swimming in the Hudson River can be safe in some locations and conditions, but safety depends on water quality, weather, strong currents, and boat traffic. Local authorities often monitor bacteria levels and issue advisories when conditions are unsafe. Swimmers should always check local guidance before entering the river.
Is the Hudson River saltwater?
The Hudson River is both freshwater and saltwater. The upper river is freshwater, while the lower 153 miles function as a tidal estuary where freshwater from inland New York mixes with saltwater from the Atlantic Ocean.
Are there sharks in the Hudson River?
Yes, sharks can occasionally enter the lower Hudson River, especially near New York Harbor where saltwater conditions exist. Species such as sand tiger sharks, bull sharks, and dogfish sharks have been reported in the estuary, although shark encounters are rare and usually occur near the river’s mouth.