State Limits on Local Zoning: By the Numbers

State efforts to create legal pathways for accessory dwelling units (ADUs) date back to the 1990s. But, until recently, state limits on local zoning for ADUs were a coastal concern. Now these laws are making inroads in the Intermountain West and the heartland.

Currently, 16 states have authorized ADU construction and occupancy by right on lots with single-family homes or in districts that permit single-family homes. Often state laws pair these allowances with maximally restrictive standards to prevent bad-faith compliance that ties by-right approvals to overly restrictive development or occupancy standards. Two other states, Maryland and Nevada, require local jurisdictions to provide a legal path for ADUs but don't prohibit them from requiring a discretionary use permit.

Most states apply these ADU limits to all local jurisdictions with zoning authority (or at least all municipalities with zoning authority). However, Colorado, Nevada, Oregon, and Washington establish population-related triggers that exempt small cities, towns, or rural counties.

Every state proposal to limit the ability of local jurisdictions to apply zoning that only permits one single-family home per lot (i.e., single-family-only zoning) is controversial. According to the National Zoning Atlas, single-family-only (SFO) zoning is the most extensively applied form of zoning in the U.S. And for many residents and local officials, the concept of SFO zoning is central to their support for the validity and necessity of zoning.

However, for all the attention that state bills targeting SFO zoning get, there have been relatively few legislative successes. Currently, only eight states have adopted limits on how local jurisdictions can apply SFO zoning. Of these, only two, California and Vermont, have enacted what amount to near-total bans on SFO zoning. And in these states the universal authorization for multiple units per residential lot only extends to duplexes. In six other states, limits on SFO zoning have jurisdiction-type, population-related, or other place-based triggers.

Additionally, California, Massachusetts, and Washington, have established transit-oriented upzoning requirements that also limit the areas where local jurisdictions can apply SFO zoning. On paper, these laws clearly align with a fundamental planning principle: frequent and cost-effective transit service depends on adequate residential density near transit stops or stations. In practice, California's law (as currently constructed) may be having the unintended consequence of discouraging communities from expanding transit service and triggering mandatory upzoning. And while transit-served cities and towns in Massachusetts are permitting more housing, new units are not primarily located within a half mile of transit stations.

The earliest local zoning ordinances were "cumulative," meaning the number and types of permissible uses increased as zoning district intensity increased. Or, to put it another way, the most-intense zoning district (e.g., a district intended for heavy industry) allowed all uses permitted in all other less-intense zoning districts (e.g., all industrial, commercial, and residential uses). In fact, this was how Euclid, Ohio's original zoning code worked, despite "Euclidean" later becoming a shorthand for zoning schemes that establish a strict separation of uses.

In the decades following World War II, the dominant form of zoning switched from cumulative to noncumulative. In noncumulative zoning, you typically can't build new residences immediately next to a factory or even a shopping mall. Many communities took this approach to its logical extreme, adopting zoning maps that divided their jurisdiction into multiple residential-only, commercial-only, and industrial-only districts.

While most recently adopted or overhauled zoning codes also include mixed-use districts that permit some combination of residential and nonresidential uses, many, if not most, communities still have multiple nonresidential-only districts on their zoning maps. Because these districts constrain opportunities to build new housing, a growing number of state legislatures are advancing a "back-to-the-future" approach to zoning that opens some or all nonresidential-only districts up to residential development.

Currently, 11 states have adopted limits on nonresidential-only zoning. Nine of these states authorize multifamily residential development by right, either as new construction or adaptive reuse of existing nonresidential structures, in districts (or portions of districts) that permit commercial uses. In Arizona, Montana, and Washington, there are population-based triggers for these authorizations. And in Florida and Oregon, new residences in nonresidential-only districts must include deed-restricted affordable housing. Meanwhile, in California and Maine, local jurisdictions must permit residences in certain nonresidential-only districts, but they can still require developers to secure a discretionary use permit.

Most states require wholesale power producers to obtain certificates of public convenience and necessity for new plants, but these certificates don't, typically, confer final siting approval. Local jurisdictions usually retain that authority for some or most facilities. However, over the past 10 years, as the market for new large-scale renewable energy facilities (mostly solar and wind) has increased dramatically, the intersection between state laws for utilities and local zoning has grown more complex.

Currently, 27 states impose some type of limit on local zoning for large-scale renewable energy facilities. Of these, 21 preempt local zoning for facilities that meet or exceed a specific power capacity threshold. While these preemptions have been on the books in some states for decades, they only became relevant to renewable energy facilities in recent years as the average size of new wind and solar facilities increased dramatically.

Six states (Illinois, Michigan, Virginia, Tennessee, Wisconsin, and Wyoming) have recently established maximally or minimally restrictive zoning standards for wind or solar facilities. In the case of Illinois and Wyoming, these standards only apply to county zoning.

Finally, four states (California, Florida, Oregon, and Washington) allow developers to choose whether they want to apply for approval through the local siting process or opt in to a state siting process. While state decisions often take longer on average than local decisions, experienced developers may view state authorities as more predictable than local officials.

Working from home obviously didn't start with COVID-19. But the pandemic normalized the practice across a wide swath of professions. It also coincided with a renewed cultural fascination with entrepreneurialism that has glamorized garage- or bedroom-based technology, retail, and entertainment startups. While most home-based businesses fly well under the radar of local code enforcement, many of these businesses are, whether they know it or not, operating in violation of local zoning regulations.

Local zoning codes have routinely included home occupation regulations for many decades now. The purpose of these regulations is to ensure that any business operated (or paid work performed) by residents as an accessory use to a dwelling doesn't negatively affect neighbors. However, the default approach in many communities makes it difficult to legally conduct any home occupation that involves employee or client visits or product shipments. While Oregon has had longstanding protections for home-based businesses in rural areas, several other states have taken recent actions to overcome local intransigence on zoning reforms for home occupations.

Currently, 15 states impose some type of limit on local zoning for home occupations. Generally, these limits function as a blanket authorization for no- or low-impact home-based work or businesses (i.e., home occupations with no or few visitors). In some states, the limits only apply to specific home occupations, such as home-based food or childcare businesses. And in Arizona and Oregon, state limits only apply to areas subject to county zoning. Some states tie the permissible scope of local regulations to objective development or operational standards. In others, local jurisdictions have more latitude, provided they do not require rezonings.

Planners and local officials in many communities across the country are navigating fierce local backlash to large-scale data center development proposals tied to the artificial intelligence (AI) buildout. While the backlash has certainly caught the attention of lawmakers in multiple states, so far, state actions have primarily targeted tax incentives and utility connection processes for data centers.

One important exception is a new law in West Virginia that preempts local zoning for data centers with rated electric loads of at least 90 MW (§5B-2-21B(c)(1)). It's too soon to tell, though, if West Virginia is on the vanguard or an outlier. New Hampshire is considering a similar bill in its current session (SB 439, 2026). But Pennsylvania lawmakers stripped data center zoning limits from an AI-related bill that has yet to come up for full vote (SB 939, 2025–2026). And Florida Governor Ron DeSantis just signed a new law explicitly protecting local zoning authority for data centers (SB 484, 2026).