This Article for the first time identifies a common law of zoning, describes the typology of this essential and overlooked element of American land use law, and establishes the historical and structural context for its pervasive set of rules and principles. Over the past 100 years, American judges, filling in the gaps and resolving the ambiguities of a surprisingly uniform set of state enabling statutes, have produced this body of common law. The story will take the reader to Iowa cornfields that surround an iconic baseball diamond; to a federal agency that gave an important impetus to the nationwide adoption of this Progressive Era tool at the state and local levels; to early railroad litigation in Massachusetts yielding a workable definition of the common law that was popularized by a legendary set of law school teaching materials; to the provisions of, and cases interpreting, other model legislation; and to the pages of dozens of state court reports from every region of the country. Critics have long raised their voices about the evils of height, area, and use controls; and commentators have directed their attention predominantly to the constitutional and environmental aspects of land use law. In the meantime, state courts, left to their own devices, have continued to frame, adapt, and reshape the common law of zoning.