A Form We Live In But No Longer Build
Missing-middle housing sits between the single-family home and the large apartment complex: duplexes, triplexes, fourplexes, townhomes, and small courtyard buildings.[2] It fits on ordinary residential lots, blends into existing neighborhoods, and rents or sells for less than a detached house because land and construction costs are shared across units.
This is not a fringe product. About 22% of the homes Americans already live in are missing-middle buildings.[3] The gap is between the stock we inherited and the stock we are adding. One is affordable and abundant; the other has nearly stopped appearing in the pipeline.
Missing Middle: What We Have vs. What We Build
Share of existing homes compared with share of new multifamily starts
Sources: U.S. Census Bureau, American Housing Survey (existing stock)[3]; NAHB Eye on Housing (production share)[1]
The Vanishing Pipeline
In an entire quarter, the nation produced only about 4,000 missing-middle starts.[1] A housing type that shelters roughly one in five American households has become an afterthought in new construction. Each year the affordable middle of the market shrinks relative to the demand for it.
Legalizing It Did Not Build It
The standard explanation is zoning: most residential land is reserved for detached single-family homes, so smaller multi-unit buildings are simply illegal to build. That is true, and reform matters. But the evidence from cities that actually changed the rules raises a harder question.
Minneapolis became the national test case when it ended single-family-only zoning citywide, legalizing duplexes, triplexes, and fourplexes on nearly every lot. The result was not a wave of new construction. From 2020 through 2024, the city permitted only about 225 duplex, triplex, and fourplex units.[4] Removing the prohibition did not, by itself, make the projects pencil out.
Minneapolis After Legalization
Duplex, triplex, and fourplex units permitted, 2020-2024, after single-family-only zoning was abolished
Source: Federal Reserve Bank of Minneapolis[4]
Why so few? Small infill projects are expensive to finance and build per unit. They are too small to attract institutional capital, too complex for most individual owners, and squeezed by construction costs, lot prices, and financing terms that favor either a single house or a large apartment block. Legalization clears the legal barrier. It does nothing about the economics.
Policy Connection
The missing middle shows why the Affordability and Immigration Act treats housing supply as an active federal responsibility, not something that follows automatically from deregulation. Zoning reform is a precondition. Getting units built takes more.
- -Policy 5 ties federal funding to housing production outcomes, rewarding jurisdictions that exceed targets and reducing funds for those that block development - closing the gap between legalization and construction.
- -Policy 5 provides infrastructure support and technical assistance for zoning reform, plus public land for housing, lowering the per-unit costs that keep small infill projects from penciling out.
- -The Minneapolis result is the case for financing: where the rules already allow missing-middle housing, federal incentives are what turn permission into supply.
Sources
- NAHB: Multifamily Missing Middle Construction Unchanged (Eye on Housing) - Missing-middle share of multifamily production and quarterly start counts
- NAHB: Housing Density and Missing Middle Housing Primer - Definition and typology of missing-middle housing
- U.S. Census Bureau: American Housing Survey - Missing-middle share of the existing U.S. housing stock (2023)
- Federal Reserve Bank of Minneapolis: Unpacking Supply and Demand in Rent Trends Since the Minneapolis 2040 Plan - Duplex, triplex, and fourplex units permitted after single-family-only zoning was abolished