The NAACP and Its Architects

American Experience

History Series / 14 Seasons

American Experience, TV's most-watched history series, brings to life the compelling stories from our past that inform our understanding of the world today.

Watch Latest: S37 E2

53m

Construction of the World Trade Center

2m 7s

The foundations themselves presented the first challenge. They would have to descend through 70 ft. of water-logged landfill before reaching bedrock. The greatest challenge by far, however, lay in the engineering of the towers themselves. The solution, developed by the structural engineers John Skilling & Leslie Robertson in the mid-1960s, was to re-conceive the basic structure of tall buildings.

Prefabrication for the Twin Towers

1m 32s

As the World Trade Center towers began to rise, another innovation made its appearance. Unlike earlier skyscrapers, assembled one column or beam at a time, the twin towers were erected in huge prefabricated components. Exterior wall sections three stories tall and floor decks 60 feet long could be lifted into place at once. The daring new technique dramatically speeded the construction process.

Safety Precautions

2m 41s

Before they could sign off on the design for the World Trade Center, engineer Leslie Robertson and his team had to consider all possible events that might take place in a high rise building. One of these possibilities was that of an airplane impact—there had been two incidences of aircraft impact on New York City skyscrapers at that time.

Tunneling and Tracklaying

43s

While tunnels were being dug through the limestone and quartzite mountains of Utah, Union Pacific workers laid track in western Wyoming. In the Wyoming desert, temperatures would soar above 100 degrees by day and fall below freezing at night.

The Task Ahead

1m 5s

Engineer Theodore Judah solved the great riddle of the Pacific Railroad when he reached Donner Pass. Judah immediately recognized the location as ideal for constructing a line through the Sierra Nevada. Judah's plans called for bridging rivers and ravines, carving 20-foot wide shelves out of sheer mountain faces and driving 18 tunnels -- one more than a 1000 feet long -- through solid granite.

Liquid Nitroglycerin and the Transcontinental Railroad

28s

The Central Pacific's best hope was a dangerous gamble: liquid nitroglycerin. Nitro was the most powerful explosive ever made, and the least stable. Transportation of liquid nitro was made illegal in California in 1867, but a British chemist came and mixed the compound on site. Liquid nitro helped the workers by blasting more rock in much less time.

Cape Horn

1m 26s

To get the railroad line across Cape Horn -- 1,300 feet above the valley floor -- workers had build a ledge for the track to run. The dangerous work involved chiseling and carving away the cliff face by hand in a narrow space just wide enough for a worker to walk through.

Summit Tunnel

1m 19s

In the fall of 1866, as the Central Pacific completed its track to Cisco, 92 miles east of Sacramento, Chinese work gangs were hurried to Donner Summit, where seven separate tunnels had to be dug. The most difficult was number six, the Summit Tunnel, 1,659 feet long and through some of the hardest rock in North America. Forty-four snow storms hit the summit that season.

Emmett Till, a Sacrificial Lamb

1m 6s

No one ever did time for the killing of Emmett Till, a fourteen year old black boy from Chicago, but his murder, and the trial and acquittal of his killers, sent a powerful message, and his sad story spurred the Civil Rights movement.

The World Learns of Emmett Till

1m 2s

50,000 people in Chicago saw Emmett Till's corpse with their own eyes. Photos of Till were published in newspapers and magazines, and even white Americans were stunned by the brutality of the murder.

The Great Migration: From Mississippi to Chicago

1m 15s

Hundreds of thousands of black people fled Mississippi for Chicago in the years between the world wars. Neighborhoods and schools were segregated, but the city offered a kind of freedom black Mississippians could only dream about.

A New Water System for Chicago

2m 49s

In response to cholera and dysentery epidemics, the Chicago Board of Sewage Commissioners selected Ellis Chesbrough to design a new water system for the city. In Chesbrough's plan, clean water from the lake bottom would pour into intakes under a crib two miles into Lake Michigan, then into an underground tunnel to a water tower. From there, clean water would flow into the city's water mains.

Chicago's Skyscrapers

57s

Skyscrapers were an efficient way to organize businesses within one building. Though skyscrapers were born in New York, the method called Chicago Construction, developed by Chicago architects and engineers between 1880 and 1883, provided the basic structural system for building modern steel-and-glass office towers.

Elevating the City

1m 33s

In response to cholera and dysentery epidemics, the Chicago Board of Sewage Commissioners selected Ellis Sylvester Chesbrough to solve Chicago’s public health crisis. Chesbrough’s planned system relied on gravity flow, but downtown streets were too low to drain into the river. New sewers raised the city's streets as much as 10 feet. The challenge then was to raise the buildings.

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