Land use guide
Seattle Zoning Explained
How land use rules shape what gets built—and what doesn't—across Seattle.
Seattle faces a housing affordability crisis, and zoning plays a central role. The city's land use code determines where housing can be built, how dense it can be, and what types of buildings are permitted. Many of these rules trace back to mid-20th-century zoning practices and have significant consequences for housing supply, neighborhood composition, and transportation patterns.1
Understanding zoning is essential for anyone interested in Seattle's housing debate. This page provides an overview of how Seattle's zoning works, why it matters, and what changes are being considered.
The scale of single-family zoning
A large share of Seattle's residential land has historically been zoned exclusively for detached single-family homes. This means that on much of Seattle's residential land, it is illegal to build a duplex, a small apartment building, or even—until recently—an accessory dwelling unit.2
This pattern is not unique to Seattle. Most American cities adopted similar zoning codes in the early-to-mid 1900s. However, the consequences have become increasingly apparent: by restricting housing supply in desirable areas, single-family zoning contributes to higher housing costs, longer commutes, and increased car dependence.1
Research in urban economics consistently shows that restrictive zoning is associated with higher housing prices. When demand for housing in a neighborhood increases but supply cannot respond, prices rise. The people priced out are typically those with lower incomes, often workers in service industries who must then commute long distances to their jobs.3 4
The missing middle
Before modern zoning, American cities featured a diversity of housing types: duplexes, triplexes, row houses, courtyard apartments, and small apartment buildings. These "missing middle" housing types provided naturally affordable options and allowed neighborhoods to accommodate residents at different life stages and income levels.5
Seattle's zoning largely eliminated this diversity. The result is a bifurcated housing market: expensive single-family homes in most neighborhoods, and larger apartment buildings concentrated along arterials and in urban villages. The gentle density that once characterized urban neighborhoods has been regulated out of existence.
Recent policy changes have begun to address this. Seattle now allows accessory dwelling units (ADUs) in single-family zones, and the city is considering broader reforms. However, the pace of change remains slow relative to the scale of the housing shortage.
Transit and land use
Zoning and transportation are deeply interconnected. Low-density zoning makes public transit financially unviable—there simply aren't enough riders per square mile to justify frequent service. This creates a feedback loop: without good transit, residents depend on cars; with car dependence entrenched, there's less political will to increase density.6
Seattle has invested heavily in light rail, yet much of the land near stations remains zoned for low-density uses. This represents a significant missed opportunity. Transit-oriented development—higher density housing near transit stations—is one of the most effective ways to reduce car dependence and create sustainable urban neighborhoods.7
The Seattle Atlas map lets you explore this relationship: toggle between zoning and transit layers to see how current land use rules align (or don't) with transit investment.
What's changing
Seattle is in the midst of updating its Comprehensive Plan, the document that guides land use policy for the next 20 years. Several zoning reforms are under consideration:8
- Station area rezoning: Increasing allowed density near light rail stations
- ADU expansion: Making it easier to build backyard cottages and basement apartments
- Missing middle legalization: Allowing duplexes, triplexes, and small apartments in more areas
- Urban village expansion: Extending areas designated for growth
These changes face political opposition from some homeowners who prefer to maintain existing neighborhood character. The debate reflects a fundamental tension in urban policy: the interests of current residents versus the needs of future residents and the broader region.
Similar debates are playing out nationally as cities reconsider zoning to increase housing supply and reuse underutilized space.9
Explore with Seattle Atlas
Seattle Atlas provides an interactive way to explore these issues. The map combines zoning data, transit routes, and proposed changes in a single interface. You can:
- View current zoning designations for any parcel
- See simplified "what can be built" categories
- Explore transit routes and bike infrastructure
- Toggle proposed zoning changes to see what's being considered
- Click any parcel for detailed information
Frequently asked questions
What is zoning?
Zoning is a set of land use regulations that determine what can be built on each parcel of land. In Seattle, zoning controls building height, density, and permitted uses—dictating whether an area can have single-family homes, apartments, retail, or industrial uses.
Why does Seattle have so much single-family zoning?
Historically, Seattle—like most American cities—adopted single-family zoning in the early 20th century. These rules were often designed to maintain neighborhood character and, in some cases, to exclude certain populations. A large share of Seattle residential land has historically been reserved for detached single-family homes. [1][2]
What is missing middle housing?
Missing middle housing refers to building types between single-family homes and large apartment complexes: duplexes, triplexes, fourplexes, townhouses, and small apartment buildings. These housing types were common before modern zoning but are now prohibited in most Seattle neighborhoods. [5]
How does zoning affect housing costs?
By restricting the supply of housing in high-demand areas, exclusionary zoning contributes to higher housing costs. When only one home can be built on a lot that could support four or more units, fewer people can live in desirable neighborhoods with good transit and jobs access. [3][4]
What zoning changes is Seattle considering?
Seattle is evaluating several zoning reforms as part of its Comprehensive Plan 2044, including expanding allowances for ADUs (accessory dwelling units), increasing density near transit stations, and potentially allowing more housing types in traditionally single-family zones. [8][10]
Sources and further reading
- New York Times (The Upshot), Cities Start to Question an American Ideal: A House With a Yard on Every Lot
- New York Times (The Upshot), Single-family zoning share by city (interactive map)
- Gyourko, J. & Molloy, R. (2015), Regulation and Housing Supply
- Hsieh, C.-T. & Moretti, E. (2019), Housing Constraints and Spatial Misallocation
- Parolek, D. (2020), Missing Middle Housing
- Ewing, R. & Cervero, R. (2010), Travel and the Built Environment: A Meta-Analysis
- National Academies Press, Transit-Oriented Development in the United States
- City of Seattle, Comprehensive Plan 2044
- Financial Times, Go zone — New York is building, baby, building
- Seattle Municipal Code, Title 23 – Land Use Code
- Sightline Institute, Legalizing Inexpensive Housing
- The Urbanist, Seattle-focused urban policy coverage
Seattle Atlas is an independent project and is not affiliated with the City of Seattle. Zoning data is sourced from official city datasets but may not reflect the most recent changes. Always verify with official sources for legal determinations.