In the nineteenth century, New York City was the nation's most populous city, its major port for goods and immigrants, and its financial center.  In the decades following the Civil War, business and industry expanded rapidly and changed dramatically.  In the antebellum era, many office functions, such as record keeping, accounting, and even meetings with suppliers, buyers, and clients, often took place in separate counting houses.  As the number and size of enterprises grew after the war, these and other office functions multiplied exponentially and were incorporated into the businesses' headquarters, necessitating more staff, more services (e.g., for training and payroll), and, consequently, more space.  

Inventions and organizational changes brought further demands for office space.  The telephone, for example, both facilitated and required the physical expansion of businesses.  Beginning in the late 1870s, the telephone connected offices throughout a building and with the outside world, thereby making it profitable to locate a business on the upper floors.  At the same time, it necessitated additional office space for telephone operators and switchboards.  Also, the trend of businesses consolidating into ever-larger corporations produced new layers of managers and their staffs, all of whom needed office space.  With available land severely limited in Manhattan, and real estate prices steep and climbing, businessmen and their architects looked skyward.

The technological breakthrough most responsible for the development of skyscrapers was the use of iron and, later, steel framing.  In the past, buildings had been constructed of wood, stone, or masonry.  Since the exteriors had to bear the weight of the floors and interior walls, buildings of any height required thick bases and exterior walls and small windows.  The iron and steel frames, though, were strong enough to bear the weight of floors and interior and exterior walls, allowing the use of thin exterior walls, large windows, more stories, and taller buildings.  

The first partial use of iron framing was the Park Theater (1795-1798) in New York City.  Iron framing was also incorporated into the construction of the Astor Library (1849-1853), as well as many theaters and stores in New York City built after mid-century.  In 1882, architect George Post pioneered the use of "cage" construction, in which an iron framework bore the weight of floors and interior walls.  Six years later, architect Bradford Gilbert advanced frame design by fully relying upon "skeleton" construction, in which the metal frame carried the weight of the exterior walls in addition to interior walls and floors.  After that, the sky was truly the limit.

A key technological advance essential to skyscrapers was the development of a safe and efficient elevator.  As early as the mid-1830s, a few factories and warehouses in England were using power-operated elevators.  In 1851, a rudimentary brake was invented by Elisha Graves from Yonkers, New York.  During the 1850s, the Crystal Palace and Fifth Avenue Hotel in New York City each had a passenger elevator, but these primitive models were slow, clumsy, expensive, and often unsafe.  The cables of these elevators wound around a large drum, the size of which could not be increased practicably for movement beyond a few stories.  

In 1870, William Hale of Chicago and Cyrus Baldwin of Boston developed the hydraulic elevator, with improvements made over the years (such as locating its components in the elevator shaft).  It soon became standard in high-rises and was manufactured widely by 1880.  Elevators allowed the upper floors to be rented readily, offsetting construction costs and making business travel more efficient.

Several other technological improvements facilitated the adoption of skyscrapers.  The problem of ventilation was solved by steam-powered fans, first manufactured in 1860, reliably efficient by 1870, and sophisticated by 1890.  (Air-conditioning developed after World War I.)  To heat the new high-rises with coal was impractical, requiring storage needs surpassing capacity and massive, frequent delivery that would block streets.  In 1881, several steam-heat ventures merged into the New York Steam Company and obtained permission from the city government to lay underground steam pipes.  

Modern plumbing had been available since mid-century, with the more advanced equipment found in hotels.  In 1880, the porcelain siphon-jet toilet was invented, and its use spread after New York's influential sanitary engineer, George Waring, recommended it the following year.  Gas lighting consumed oxygen, generated heat, and presented a fire hazard; so electrical lighting was incorporated pervasively in the tall buildings of the 1880s.  Steam-powered construction equipment had been around since mid-century, but its high cost prevented widespread use.  By the 1890s, however, labor costs forced most construction companies to turn to steam and, later, electric power equipment.

While some deny the label "skyscraper" to buildings under ten stories or with weight-bearing exterior walls, many scholars now emphasize important prototypes in New York City.  The seven-and-a-half-story Equitable Building (1868-1870), designed by George Post for the Equitable Life Assurance Society, used interior iron-framing extensively and demonstrated the benefit of elevators.  Post's Western Union Building (1872-1875) and Richard Morris Hunt's Tribune Building (1873-1875) were remarkable for their ten-story height.  The economic depression of the mid- and late-1870s inhibited construction, but a building boom exploded in the 1880s with structures in New York City and Chicago stretching ever higher.  At the skyscraper's inception, cartoonist Nast perceptively realized its long-term results.

As mentioned above, George Post set crucial precedents when he used cage-frame construction in the overall design of the Produce Exchange Building (1882-1884), and skeleton construction in its interior courts.  In 1888, Bradford Gilbert provoked widespread criticism and skepticism when he announced plans to erect an 11-story, 158-foot building, dependent solely upon skeleton construction.  It was widely believed that such a tall, exterior frame could not safely withstand high winds.  Gilbert, though, pointed to Gustave Eiffel's recent completion of such a structure for the 151-foot Statue of Liberty (1886).  When work on Gilbert's Tower Building in New York City reached the tenth story, a strong windstorm arrived, enticing a crowd of people to gather nearby and watch the building topple over.  Instead, Gilbert fearlessly climbed to the top and dropped a plumb line, demonstrating no sway in the building.

Joseph Pulitzer, publisher of the New York World, commissioned Post to construct (1889-1890) new headquarters for the newspaper at Park Row and Frankfort Street.  Reaching an amazing height of 309 feet, with 18-26 stories (depending on definition), the structure easily became the tallest building on the planet, vastly overshadowing the surrounding offices of rival newspapers.  The delighted World editors bragged that they could lean out theirs windows and "spit on the Sun."  

The skyline of New York City continued to elevate during the 1890s, while the Chicago government placed a ceiling in 1893 on the upper limits of buildings.  By the end of the decade, more than 300 buildings in Manhattan stood over nine stories tall.  It was also during the 1890s that the term "skyscraper" first came into prevalent use to describe the tall buildings.  Harper's Weekly first used the word in 1893.