In 1892 the New York Building Law made its first provisions for skeleton constructions. There followed a period of experimentation to devise efficient floor plans and aesthetically satisfying forms. In New York City the Flatiron Building by D. H. Burnham was constructed in 1902, the Metropolitan Life Insurance Tower in 1909, and the Woolworth Building, 60 stories high, by Cass Gilbert, in 1913. The last, with Gothic ornamentation, exemplifies the general tendency at that time to adapt earlier architectural styles to modern construction. The radical innovator Louis Henry Sullivan gave impetus to a new, bold aesthetic for skyscrapers. An excellent example is his design for the Wainwright building in St. Louis (1890–91). Frank Lloyd Wright also contributed his unorthodox vision to such structures as the Price Tower (1953) in Bartlesville, Okla.
In 1916, New York City adopted the Building Zone Resolution, establishing legal control over the height and plan of buildings and over the factors relating to health, fire hazard, and assurance of adequate light and air to buildings and streets. Regulations regarding the setting back of exterior walls above a determined height, largely intended to allow light to reach the streets, gave rise to buildings whose stepped profiles characterize the American skyscraper of subsequent years.
With the complex structural and planning problems solved, architects still seek solutions to the difficulties of integrating skyscrapers with community requirements of hygiene, transportation, and commercial interest. In New York during the 1950s, public plazas were incorporated into the designs of the Lever House by Gordon Bunshaft and the Seagram Building of Mies van der Rohe. These International style buildings are also examples of the effective use of vast expanses of glass in skyscrapers. More recently, numerous skyscrapers have been constructed in a number of postmodern modes.