By Steve Swedberg, Competitive Enterprise Institute
When Americans think about the housing affordability debate, they tend to picture cranes, lumber prices, or mortgage interest rates. It is certainly important to focus on such aspects as environmental reviews, design mandates, tariffs, and approval times. However, this assumes that high housing costs are due exclusively to construction expenses.
Far less media attention is paid to barriers to housing affordability that appear before ground is broken. Across the country, local land-use rules quietly restrict what can be built and how housing can be developed. One such regulation is the minimum lot size (MLS).
A minimum lot size is a zoning regulation that mandates a set amount of land for each residential unit. In practice, MLS rules determine how much land must accompany every home before any plans are drawn up or permits are requested. The real significance of an MLS becomes clearer once we examine how they alter the incentives and constraints facing landowners, builders, and buyers.
By setting a legal floor on parcel size, an MLS limits the ways land can be subdivided or developed. Rather than adjusting to block-by-block conditions, MLS rules impose a uniform parcel-size requirement within covered zones, even when market demand would support smaller lots.
Fewer homes, bigger yards
By definition, MLS rules restrict housing supply. When a jurisdiction mandates that each home sits on a large parcel, fewer homes can be built on that fixed amount of land. Using parcel-level data from thousands of jurisdictions, researchers at the National Bureau of Economic Research (NBER) established that stricter MLS regulations reduced housing density by about 11 percent compared to less restrictive neighboring jurisdictions.
MLS rules restrict both current and future housing supply now. A study from the University of Louisville found that MLS regulations delay the conversion of vacant land and slow the demolition and replacement of existing housing. This dampens redevelopment and further constrains long‑run housing supply growth.
The NBER study also shows that MLS regulations dramatically increase land consumption while only modestly increasing living space. Stricter MLS rules increase house size by roughly 80 square feet (or 4 percent), whereas the average lot expands by about 3,000 square feet (or 37 percent). For every additional square foot of living space, roughly 37 additional square feet of land are required. In other words, MLS regulations are lawn and landscaping mandates masquerading as housing policy.
More grass, less cash
All that mandated yard space comes at a cost. An MLS regulation drives up the price of every affected home. A professor at the University of Colorado-Boulder analyzed nationwide data and calculated that doubling the minimum lot size increases home sales prices by 14 percent and rents by 9 percent. Going back to the NBER study, house prices are nearly $30,000 higher with stricter MLS in comparison to the least regulated. All of that extra lawn space translates directly into higher housing costs.
Historic rationales and their outdated assumptions
Given these costs, the question is why these rules exist in the first place. While MLS regulations date back to the early 20th century, it really gained prominence in the late 1940s. After World War II, many suburban governments adopted MLS rules as a form of fiscal zoning. The concern was that dense development would bring in lower-value homes and more school-age children, straining municipal budgets. Larger lots were seen as a way to boost tax base per household while limiting service demands. In effect, MLS became a blunt instrument for stabilizing the tax base.
Since property taxes are tied to assessed value rather than parcel size, fiscal balance can be achieved through rate adjustments and efficient service provision without restricting density. Evidence from New Hampshire illustrates that higher property tax rates are associated with smaller residential lots, which indicates that local governments can secure revenue through tax policy rather than density restrictions.
Public health concerns were another early rationale. Policymakers feared overcrowding, contaminated water, and inadequate waste disposal, especially in dense urban areas. However, by the time MLS became widespread in the late 1940s and 1950s, the public health risks that once justified minimum land standards had largely been mitigated by modern technology.
The introduction of water filtration and chlorine in major US cities accounted forabout one-half of the 30 percent decline in urban death rates between 1900 and 1940. Census data show that about two-thirds of homes had indoor plumbing by 1950, a figure that increased to over 80 percent by 1960 and 99 percent by 1990. Modern housing is built to the Uniform Plumbing Code, which ensures safe water supply and waste removal even in dense neighborhoods. In short, the health rationale for MLS has all but vanished.
Another oft-cited rationale for MLS is aesthetics. Proponents believe that uniform, spacious lots create more attractive, orderly communities. While appealing in theory, this argument is subjective and largely serves to justify exclusionary practices rather than address any tangible public need. In practice, mandating lot size to preserve “curb appeal” does little beyond restricting density, inflating housing costs, and enforcing uniformity on neighborhoods that might thrive with more diverse housing forms.
The so-called “value gains” from MLS regulations reflect artificial price premiums, not better-quality homes. Taken together, the technological, sanitary, and aesthetic justifications that once supported MLS rules no longer carry practical weight, leaving these regulations as a costly relic rather than a necessity.
Let markets, not mandates, decide
Compared to other topics, minimum lot size requirements receive less attention in housing policy debates, yet they quietly shape how much housing can be built and how much families must pay for it. By legally fixing the amount of land required per home, MLS rules artificially create scarcity. The result is predictable: higher land consumption, slower redevelopment, and elevated housing costs driven by artificial limits on supply rather than genuine improvements in quality.
Reform does not need to be radical. It means updating land-use rules to reflect present realities rather than a mid-20th century mindset. Municipalities can scale back or eliminate lot-size minimums, which allows smaller parcels where infrastructure can support them. They can also permit administrative lot splits, which let a landowner divide a property into multiple smaller lots without lengthy zoning hearings. There is the option of enabling by-right infill development, thereby allowing new homes or duplexes on underused lots without special approvals.
Municipalities can likewise permit accessory dwelling units (ADUs) by right, which would allow incremental additions to housing supply without fundamentally altering neighborhood form. As localities consider such reforms, recent decisions by Fannie Mae to incorporate ADU-related financing into their portfolios signal that secondary mortgage markets are adapting to support these locally authorized housing options.
Municipalities can also adopt tradeable development credits, a system that allows developers who want to build more densely to purchase credits from other landowners who preserve larger lots elsewhere. This market-based approach lets overall minimum lot size requirements remain in place while directing growth to areas where higher density is most suitable, which can enable more housing without a blanket reduction of MLS rules.
States can similarly act to preempt overly restrictive local rules, ensuring that MLS mandates do not artificially constrain housing supply across an entire region. While state-level action may face pushback from municipalities that want to retain local control, it provides a pathway to remove entrenched barriers that inflate costs and slow housing construction.
If housing affordability is a priority, policymakers should begin by examining the rules that preemptively constrain supply. Removing or reducing minimum lot sizes would not solve every challenge in housing policy, but it would eliminate a costly relic that inflates prices without delivering commensurate public benefits.
Steve Swedberg is a Policy Analyst with the Center for Economic Freedom, focusing on financial, monetary, and transportation policy.