Tappan Zee Bridge

historic significance

Although discussion and debate of a Hudson River crossing began in the 1800s, countless obstacles stood in the way, including fierce local opposition and challenging engineering problems. By the 1950s, the tides had changed: Political consensus and engineering advances made it possible to embark on building what would be one of the most innovative bridges of its time in the United States.

Archival image of the Tappan Zee Bridge with an icy Hudson River

Cost to build the Tappan Zee Bridge


breakthrough engineering

The area of the Hudson known as the Tappan Zee (named for the Native American Tappan people who once lived in the area and the Dutch word for “sea”) is a natural widening of the river that’s 10 miles long and three miles wide in places. To stabilize a bridge that would cross the river at one of its widest points, engineers had to tackle a substantial problem: how to provide massive foundations for a 1,212-ft wide navigation channel when the bedrock needed to anchor them was at a depth of approximately 250 feet. The common solution available in 1950 was to use long steel piles, but the number of piles needed represented an astronomical — and unaffordable — cost.

caisson labeled

Drawing on experience gained building temporary harbors for the Allied Forces during World War II, engineer Emil H. Praeger devised a novel solution that would eliminate the need to anchor everything to bedrock: use the river’s natural buoyancy to support some of the weight. So, when the nearly $81 million Tappan Zee Bridge (more than $760 million in today’s dollars) opened in 1955, it was the first permanent bridge in the U.S. to be supported in part by airtight floating concrete boxes (it was also the ninth longest span in the world). These eight giant buoyant caissons provided enough upward force to carry 70-80 percent of the weight of the span and its load of traffic over the navigation channel. The approach made engineering history and the bridge earned a place on the National Register of Historic Places.

The Need for a New Bridge

The increasing spread of suburban communities through the Hudson Valley and the accompanying rise of automobile use made a river crossing north of New York City an urgent necessity by the start of the 1950s, although the need had been anticipated long before. In fact, 20 years before the bridge opened (and only four years after the opening of the George Washington Bridge in 1931), the U.S. Congress approved funding for a crossing between Nyack and Tarrytown . Over the years, many different sites were considered but, ultimately, the South Nyack/Tarrytown location was selected, in part, to avoid sharing toll revenue with New Jersey.

The Bear Mountain Bridge opened in 1924, connecting Westchester/Putnam counties on the eastern shore of the Hudson River with Rockland/Orange counties.

Beyond connecting population centers and regional highways in Rockland and Westchester counties, the Tappan Zee Bridge was a vital link between the upstate and downstate sections of the New York State Thruway. Approved in 1942, the Thruway started construction in 1946 near Syracuse. When the Tappan Zee Bridge opened nine years later, it linked the two portions of the roadway, giving the Thruway mainline a total length of 423 miles – the longest operating toll expressway in the nation. By the end of 1960, all 559 miles of the Thruway system were open, connecting Buffalo on the shores of Lake Erie, the state capital of Albany, and New York City. Prior to the Tappan Zee, the nearest Hudson River crossing to the George Washington Bridge  was 44 miles.

Driving Growth and Opportunity

From the day it opened in December 1955, the Tappan Zee Bridge powered significant economic currents on both sides of the river. Its impact was most dramatic in Rockland County, which evolved rapidly from a predominantly rural and agricultural area to a diverse and bustling suburb. In the first five years after the bridge opened, the county’s population increased 50 percent.

Photo Credit: Gerber Collection, Town of Clarkstown



Within a decade, 500,000 square feet of industrial space was under construction in the county to satisfy the demands of the businesses and manufacturing companies that seized the opportunities the new bridge offered. By 1965, Rockland was averaging more than 3,000 new residential units per year , along with new post offices and other public services, including schools. Growth did not come without a cost, however: construction of the bridge displaced more than 100 homes in South Nyack as well as the village’s commercial center.

By contrast, the physical impact of the bridge in Tarrytown was far less extensive. Only a few small homes and one large estate - Hawthorne – had to come down to make room for construction of the new bridge. The social and economic impact of the bridge in Tarrytown and the adjoining communities in Westchester County, however, was substantial. The addition of the Tappan Zee to Westchester’s transportation corridor attracted hundreds of millions of dollars in new residential development to house a growing population, along with large-scale commercial construction for corporate giants such as General Motors, General Foods, and IBM. The opening in 1960 of the Cross Westchester Expressway (I-287) linked Rockland and Westchester with Connecticut and New England, and paved the way for a new corporate mecca parallel to I-287, known today as the Platinum Mile.

Looking east over downtown New City and surrounding developments. In the background, Lake DeForest and the causeway are visible, as are Congers and the Hudson River. Photo Credit: Gerber Collection, Town of Clarkstown

Gateway to a New Beginning

In Rockland and Westchester, new jobs stimulated population growth and housing demand for workers benefiting from the expanding job market and the growing opportunities on both sides of the Tappan Zee Bridge. Creating an important new gateway for the movement of people, goods, services, and materials, the bridge provided access to attractive locations for new corporate tenants and businesses in a burgeoning suburban region while providing industry with a fast and reliable river crossing.