The Hudson River begins as a trickle at Lake Tear of the Clouds in northern New York State, then travels southward 315 miles before emptying into Upper New York Bay and then into the Atlantic Ocean. Its lower half is a tidal estuary; its rising and falling tides influence the Hudson’s current as far north as Troy, New York.

For hundreds of years there was no way to cross the Hudson except by boat. Now there are many bridges—at least 45 at last count. With a new Tappan Zee Bridge about to begin construction, here are some details about a few of the other bridges that cross the mighty Hudson.

Tappan Zee Bridge

Opened 56 years ago, on Dec 15, 1955, the

Tappan Zee is a cantilever bridge. Its site, the second-widest point on the river, added to construction costs but was chosen to be as close as possible to New York City, while staying outside the Port Authority’s 25-mile area of influence. This ensured that revenue from tolls went to the newly-created NY State Thruway Authority and not to the Port Authority. A unique aspect of its design is that the main span is supported by eight hollow concrete caissons. Their buoyancy carries some of the load and helped to reduce construction costs.

Bear Mountain Bridge

Opened 87 years ago on Nov 27, 1924. At its formal opening, it was the longest suspension bridge span in the world, and the first of its type to have a concrete deck. It held the record for world’s longest suspension bridge for 19 months, until it was surpassed by the Benjamin Franklin Bridge in Philadelphia. It was the first automobile bridge to cross the Hudson south of Albany and surpassed the 1888 Poughkeepsie Railroad Bridge as the southernmost crossing of the river. .Construction methods pioneered on the Bear Mountain Bridge influenced much larger projects to follow, including the George Washington (1931) and Golden Gate (1937)

George Washington Bridge

Its upper level opened 81 years ago, on Oct 24, 1931; its lower level opened 50 years ago on Aug 29, 1962. It is a 4,760 foot suspension bridge spanning the Hudson, connecting NY City to Fort Lee, NJ. When it opened, it surpassed Detroit’s Ambassador Bridge for the longest main span in the world, nearly doubling the previous record. The GW held this title until the opening of the Golden Gate Bridge in 1937.

Mid-Hudson Bridge

Opened 82 years ago on Aug 25, 1930. It is a suspension bridge which carries US 44 and NY 55 across the Hudson between Poughkeepsie and Highland. The bridge is 3,000 feet long with a clearance of 135 feet. At its opening, it was the sixth-longest suspension bridge in the world. At the time, except for ferries, there was no crossing the river south of Albany. The Bear Mountain Bridge in Westchester County and the Holland Tunnel in Manhattan were under construction at that time.

Rip Van Winkle Bridge

Opened 77 years ago on July 2, 1935 at a cost of $2.4 million. It is a cantilever bridge spanning the Hudson River between Hudson, NY and Catskill, NY. The structure carries NY 23 across the river, connecting on the West side, US 9W and NY 385 with NY 9G on the East side. The bridge was built by the newly-created NY State Bridge Authority. At its opening, the toll was 80¢ per passenger car and 10¢ per passenger up to $1. The current toll for autos is $1.50 for eastbound traffic only. It extends 5,040 feet across the river, with a ship clearance of 145 feet.

Poughkeepsie Bridge

Opened 123 years ago on Jan 1, 1889 as a railroad bridge; 3 years ago, on Oct 3, 2009 as a pedestrian and bicycle bridge. Known also as the Poughkeepsie Railroad Bridge, the High Bridge and, for the last three years, as the Walkway Over the Hudson State Historic Park. It is a steel cantilever bridge spanning the Hudson River between Poughkeepsie, NY on the East bank and Highland, NY on the West bank. It served as a double track railroad bridge from 1889 until it went out of service in 1974. Listed on the National Register of Historic Places in 1979 and updated in 2008, it opened to the public on Oct 3, 2009 as a pedestrian and cyclist bridge and New York State Park. It may be the world’s longest footbridge.

Menands Bridge

Built 79 years ago, in 1933, Troy-Menands Bridge (its official name), carries NY State Route 378 across the Hudson River in New York connecting Menands with Troy. A through truss span, the bridge was built to accommodate tall ships and once featured a pair of elevating towers. The lifting device was removed in 1966, but the towers remained until their removal in the summer of 2000.

The path Westward

In the 1600s the Hudson Valley was described as inhospitable, filled with wild animals and poisonous snakes. The mountains were said to be covered with dangerous forests The river was seen as treacherous.

But in the next hundred years people turned the river into a well-traveled pathway and the land into prosperous farms and villages

In the 1800s, before bridges and roads, the river was the best way to transport goods North and West. River transport was by raft, then Hudson river sloop and later, by side-wheel steamboats. These offered a fast, affordable way to travel. By 1850 there were about 150 boats steaming up and down the Hudson.

To carry produce to markets in the Midwest cheaply and safely, the Erie Canal was constructed, connecting the Hudson to Lake Ontario; it opened in 1817 and proved to be an economic bonanza and made New York the Empire State.