Columbus, Ohio attached the first known off-street parking requirement to new apartment buildings in 1923, and within three decades almost every American zoning code specified minimum space counts per dwelling, per seat or per thousand square feet of floor area. The ratios were copied between cities and from trade manuals rather than measured, and ratcheted upward: a Columbus building of 100 one-bedroom flats needed 100 spaces in 1954 and 150 by 2022. Donald Shoup's work showed the requirements force parking to be supplied in bulk and priced at zero, with the cost buried in rents and prices. Buffalo abolished its minimums citywide in 2017, and repeals have since spread to state law, including California's AB 2097 in 2022.
Parking minimums quietly set the density, plot coverage, setback and financial viability of American development, often devoting more site area to cars than to buildings and making walkable mid-rise infill mathematically impossible. Their rollback since 2017 is the largest deregulation of urban form in a century, and the clearest case of a technical zoning standard shaping a continent's built environment.
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