The Standard State Zoning Enabling Act, issued by the US Department of Commerce in 1924 (revised 1926) under Secretary Herbert Hoover, was a model statute that states could adopt to authorise their municipalities to regulate land. It let cities divide their territory into districts and set restrictions on the use, height and bulk of buildings within each. As a model act it was not itself binding law but a template for state legislatures. Most states enacted versions of it within a few years.
It standardised and spread Euclidean (use-based) zoning, which the Supreme Court upheld in 1926, making it the dominant land-use regulatory tool across the United States. Its district-and-bulk framework shaped American urban form, separating uses and entrenching low-density residential zones for the rest of the century.