Free Mesothelioma Information Packet

World Trade Center History and Construction

World Trade Center

Everyone remembers the day the World Trade Center (WTC) towers came down, but not everyone recalls the glory days of the towers, from their conception in the 1960s until their collapse on September 11, 2001.

Designing a Plan

The idea to build a World Trade Center in New York City was conceived by the Downtown-Lower Manhattan Development Corporation around 1962, when the area around the Battery was beginning to deteriorate. New York's Rockefeller family was largely responsible for promoting this project and urging the Port Authority of New York and New Jersey to seriously consider this revitalization plan.

Architect Minoru Yamasaki and Associates of Michigan were chosen to render the designs, and after much discussion as to the shape the project might take, Yamasaki decided on two rather plain towers that would stand about 80-90 stories high. It wasn't until later that the idea of making the World Trade Center towers "the tallest in the world" was devised. This monolithic design had plenty of opponents, but by 1966, final approval was given and construction began.

Building the Towers

Much of Lower Manhattan had to be disrupted in order to build the World Trade Center complex. Numerous streets were closed and massive amounts of earth were moved. Much of the landfill was later used in the construction of Battery Park City, which sits at the tip of the island and consists of homes, stores, and recreation areas for those who live and work in that area of Manhattan. More than 150 buildings were demolished to make room for the towers and the other smaller World Trade Center complex buildings that would surround them.

Statistics show that approximately 10,000 construction workers toiled at the site, with about 3,500 working together during peak construction periods. Construction accidents caused the death of 60 people.

The north tower was the first to open in December 1970. The south tower followed just a little more than a year later, in January 1972, though many of the upper floors in both towers were not completed until the end of 1972 or sometime in 1973. The towers immediately achieved fame as the "Tallest Buildings in the World", at 1,368 and 1,362 feet, respectively. Their reign was short as the Chicago Sears Tower surpassed them less than 2 years later.

Experts say construction of the buildings involved the use of 200,000 tons of steel and 425,000 cubic yards of concrete, and that the towers contained 43,600 windows, and 12,000 miles of electric cable. The complex was so massive that it had its own zip code! The pedestrian shopping mall below the WTC was the largest in Manhattan and there were 2 subway stations and a New Jersey PATH train station underneath as well.

During the thirty years that the towers stood, an estimated 50,000 people worked there each day. Some estimate that four times that number passed through the buildings daily.

Their Unique Construction

Designing very tall buildings can be tricky. Stability is a huge consideration in constructing skyscrapers.

Engineers for the WTC used an innovative design. The towers were hollow tubes of closely-spaced steel columns, with floor trusses extending across to a central core. The columns were finished with a silver-colored aluminum alloy. For the first time in the building of a skyscraper, there was no masonry used in the construction of the World Trade Center towers.

The core and elevator systems were also unique. Worried that the intense air pressure created by the buildings' high speed elevators might buckle conventional shafts, engineers designed a solution using a drywall system fixed to the reinforced steel core. In addition, all the elevators did not serve all 110 floors. If so, the operating systems would have consumed too much space. Instead, there were 2 lift systems: an express bank of elevators and another group of "local" elevators. Passengers would change elevators at so-called sky lobbies located on the 44th and 78th floors. That halved the number of shafts needed to accommodate the elevators.

More on the World Trade Center, 9/11, and Asbestos

Last modified: December 28, 2010.