The basic foundation for planning and zoning in the U.S. was laid by two standard state enabling acts published by the U.S. Department of Commerce in the 1920s. For many states, the Standard Acts, as they are known, still supply the institutional structure, although some procedural and substantive components may have changed.
The first, A Standard State Zoning Enabling Act (SZEA), was developed by an advisory committee on zoning appointed by Secretary of Commerce (and later President) Herbert Hoover in 1921. After several revisions, the Government Printing Office published the first printed edition in May 1924, and a revised edition in 1926.
The SZEA had nine sections. It included a grant of power, a provision that the legislative body could divide the local government's territory into districts, a statement of purpose for the zoning regulations, and procedures for establishing and amending the zoning regulations. A legislative body was required to establish a zoning commission to advise it on the initial development of zoning regulations.
In March 1927, a preliminary edition of the second model, A Standard City Planning Enabling Act (SCPEA), was released, and a final version was published in 1928. The SCPEA covered six subjects:
The first Standard State Zoning Enabling Act, (or "SZEA") was written by a New York City commission headed by Edward Bassett and signed by Mayor John Purroy Mitchel in 1916 to regulate buildings and land usage in New York City. It was brought forth as part of the reaction to the construction of the Equitable Building which still stands at 120 Broadway. The building towered over the neighboring residences, completely covering all available land area within the property boundary, blocking windows of neighboring buildings and diminishing the availability of sunshine for the people in the affected area. These laws became the blueprint for zoning in the rest of the United States, because they were accepted almost without change by most states.
The setback code led to adoption of styles such as that of the Chrysler Building and Empire State Building with tiered architecture in its top floors. The effect of the zoning regulations on the shape of skyscrapers was famously illustrated by architect and illustrator Hugh Ferriss.
By the 1960s, many architects had responded to the code by adopting the plaza style of architecture, in which vertical buildings rose from the middle of a concrete plaza, such as the Twin Towers of the World Trade Center.