Skyscrapers in architecture

The most notable United States architectural innovation has been the skyscraper. Several technical advances made this possible. In 1853 Elisha Otis invented the first safety elevator which prevented a car from falling down the shaft if the suspending cable broke.

Elevators allowed buildings to rise above the four or five stories that people were willing to climb by stairs for normal occupancy. An 1868 competition decided the design of New York City's six story Equitable Life Building, which would become the first commercial building to use an elevator. Construction commenced in 1873. Other structures followed such as the Auditorium Building, Chicago in 1885 by Dankmar Adler and Louis Sullivan. This adopted Italian palazzo design details to give the appearance of a structured whole: for several decades American skyscrapers would blend conservative decorative elements with technical innovation.

Soon skyscrapers encountered a new technological challenge. Load bearing stone walls become impractical as a structure gains height, reaching a technical limit at about 20 stories. Professional engineer William LeBaron Jenney solved the problem with a steel support frame in Chicago's 10 story Home Insurance Building, 1885. Arguably this is the first true skyscraper. The use of a thin curtain wall in place of a load bearing wall reduced the building's overall weight by two thirds.
Another feature that was to become familiar in twentieth century skyscrapers first appeared in Chicago's Reliance Building, designed by Charles B. Atwood and E.C. Shankland, Chicago, 1890 - 1895. Because outer walls no longer bore the weight of a building it was possible to increase window size. This became the first skyscraper to have plate glass windows take up a majority of its outer surface area.

One culturally significant early skyscraper was New York City's Woolworth Building designed by architect Cass Gilbert, 1913. Raising previous technological advances to new heights, 792 ft (241 m), it was the world's tallest building until 1930. Frank Woolworth was fond of gothic cathedrals. Cass Gilbert constructed the office building as a cathedral of commerce and incorporated many Gothic revival decorative elements. The main entrance and lobby contain numerous allegories of thrift, including an acorn growing into an oak tree and a man losing his shirt. Security concerns following the attack on the nearby World Trade Center have closed the lobby to public viewing. The popularity of the new Woolworth Building inspired many Gothic revival imitations among skyscrapers and remained a popular design theme until the art deco era. Other public concerns emerged following the building's introduction. The Woolworth Building blocked a significant amount of sunlight to the neighborhood. This inspired the New York City setback law that remained in effect until 1960. Basically the law allowed a structure to rise to any height as long as it reduced the area of each tower floor to one quarter of the structure's ground floor area.