Advocates for housing affordability are zeroing in on one of the lesser-known reasons why homes are so pricey across the US: the minimum lot size.

Zoning regulations that say single-family homes can only be built on large parcels of land are surprisingly common. An analysis by the National Zoning Atlas shows that 56% of single-family residential land in studied US areas requires lots of at least 40,000 square feet — the “builder’s acre” as it is commonly known. That’s about the size of a football field.

In Massachusetts, where more than half of single-family zoned land requires a large lot, voters are set to decide on a ballot question that would shrink the size of land required for homes, from that football field to about the size of a basketball court.

Question 7, billed as a way to legalize starter homes, would establish a statewide minimum lot size of 5,000 square feet for cities and towns with water and sewer service. Overriding local land use regulations is necessary, advocates say, to increase the supply of smaller, more affordable homes for families to begin the journey of home ownership. The cost of housing in Massachusetts, where the median home price is north of $650,000 and there’s an estimated supply shortfall of 220,000 homes, is driving people away and hobbling the economy, state officials say.

“Minimum lot size requirements raise the cost of housing both directly because land costs money, and indirectly because they’re essentially placing a cap on the number of homes you can have in a given area, thereby increasing buyer competition for the few remaining homes,” said Andrew Mikula, chief housing economist at the think tank Pioneer Institute and chair of the Legalize Starter Homes campaign.

Passing the measure could prompt the construction of 2,200 to 5,700 new homes per year, according to the campaign, mostly in suburbs outside Boston and other cities. An estimate by the Center for State Policy Analysis at Tufts University was more modest: about 750 new homes per year.

Backers of the measure range from the Greater Boston Real Estate Board to the Boston Chapter of the Democratic Socialists of America and Progressive Mass, and also include the governor and mayors of numerous cities, including Boston. It’s a big tent that reflects the breadth of the pro-housing Yes in My Backyard movement, which has helped inspire a slew of other housing-related ballot questions — in Hawaii, California and Rhode Island — that similarly seek to lift restrictions and increase supply.

The focus on large lot sizes — including new legislation to remove restrictions that require minimum lot sizes of more than 2,000 square feet for single-family homes in Colorado — comes after a wave of other zoning reforms, legalizing accessory dwelling units, eliminating parking minimums and streamlining permitting. Lot size is the next logical YIMBY target: Texas and Idaho are among the states that have already passed small-lot mandates.

Though not top of mind for most people, minimum lot sizes are ingrained in the American landscape. The requirements became standard operating procedure over the course of the 20th century, as growth increased rapidly in suburban communities in the orbit of metropolitan areas. The percentage of single-family-zoned land requiring large lots varies by the state — 68% in New Mexico, 74% in both Arizona and Connecticut, 81% in Colorado, and a full 89% in Vermont, according to the National Zoning Atlas.

In many cases, the minimum lot size is two acres. Only about 4% of single-family-zoned land allows small lots of under 10,000 square feet.

Their adoption may have been initially spurred by a concern that small lots and starter homes wouldn’t pay sufficient property taxes, according to an analysis by the Mercatus Institute. Critics say the requirements ended up being an entirely intentional policy aimed at limiting the number of homes — and people — by strictly limiting density. Established homeowners fight to protect the resulting landscape, often arguing that community character must be maintained.

“Zoning has made sprawl the norm — and people are tired of it,” said Sara Bronin, founder of the National Zoning Atlas, which recently spun off a new entity for geospatial and data analysis probing land use rules called Land Use Labs.

The environmental impacts of this land use framework have been well-documented. New residential development has essentially been legally required to push out into farmland and wilderness. Economists describe it as a regulatory-induced inefficiency, as there is no opportunity to consolidate growth more compactly.

With land in popular metropolitan areas so expensive, the requirements mean that a million-dollar McMansion is often the only product that makes financial sense for developers. The “starter home” — with a size of, say, 1,500 square feet, which was the average single-family home size in 1970 before ballooning to today’s 2,400 square feet — is increasingly rare. Competition for existing small homes close to and within urban centers is intense, and made more so by rising corporate ownership.

“Massachusetts is the hardest state in the country for young adults to buy a home. The middle class is shrinking because the cost of housing has exploded,” Mikula said.

Opponents of Question 7 begin with a familiar objection: the loss of local control. Statewide zoning reform measures passed in recent years are a form of preemption of municipal government; land use, in the American tradition, is a local affair. A common refrain is that every community is different, and that a statewide lot size is the definition of a one-size-fits-all policy.

But the real problem with Question 7 is that it won’t produce the affordability it promises, according to Adam Chapdelaine, executive director of the Massachusetts Municipal Association, representing the commonwealth’s 351 cities and towns. He argues that, without guardrails like a limit on the size of homes on small lots, developers will gravitate toward what’s most profitable for them. “The risk with this ballot question is that we would overrule local zoning authority and bypass any local public input in our communities only to wind up with more high-end housing — which would exacerbate the lack of starter homes, not fix it,” Chapdelaine said.

There is some empirical evidence that reducing lot size does bring down prices. In Houston, which started to reduce requirements 25 years ago from 5,000 to 1,400 square feet, thousands of new homes were built that cost about 40% less than single-family homes on large lots, according to a study by the Pew Charitable Trusts.

Addressing minimum lot sizes can be considered as one part of a “silver buckshot” approach that encourages the construction of more housing. Some of this can be done through incentives, like the 40Y starter home program in Massachusetts, launched in 2022, which provides state funding if communities create zoning districts for first-time homebuyers or downsizing households.

Still, local jurisdictions have myriad ways of foiling residential growth, said Jonathan Berk, author of the recent Boston Foundation report “Delayed by Design: How Discretionary Permitting Stalls Development in Massachusetts.”Backyard ADUs were legalized across Massachusetts, in 2025, for example, but local regulatory processes have slowed their adoption; requirements around stormwater management, septic systems, site plan review and other local permitting requirements “can add significant cost, delay, and, most importantly, uncertainty for homeowners and small builders,” Berk said.

If Question 7 passes, the same kind of end-run will likely occur, Berk said, unless further reforms on things like discretionary site plan review — where municipalities can nitpick layouts and design over months or years — are also passed.

In other words, the YIMBYs of Massachusetts will need to stay on offense; after all, they’re facing off against a regulatory regime that has been ensconced for a century. One need only look at all those homes on football fields to appreciate how powerful land use rules can be.