When combined with a height district, a control over volume occurred. Together these dimensions resulted in a limit on the percentage of lots covered by structures. The area districts were not defined by minimum lot sizes, as might be supposed, but by minimum yard and court dimensions. New York city decided on separate use, height, and area districts. Their recommendations formed the bases of the first zoning ordinances adopted in these two large cities. The evils of tall buildings, crowded together on land parcels too small and streets too narrow, were explored by special commissions appointed in 19 by the Board of Estimate and Apportionment of the City of New York and in 1923 by the Chicago Real Estate Board. The first purpose of zoning in the United States was to control bulk. Williams, in Model Laws for Planning Cities, Counties, and States, Harvard City Planning Studies, Vol. For the purpose of promoting health, safety, morals, or the general welfare of the community, the legislative body of every municipality is hereby empowered to regulate and restrict the height, number of stories, and size of buildings and other structures, the percentage of lot that may be occupied, the size of yards, courts, and other open spaces, the density of population, and the location and use of buildings, structures, and land for trade, industry, residence, or other purposes. Membership for Allied Professionals & Citizensġ313 EAST 60TH STREET - CHICAGO 37 ILLINOIS