Introduction
Across the United States, millions are spending more than half their income on rent as the nation’s severe shortage of affordable housing continues. In response, policymakers are being urged to prioritize affordable housing by reducing regulatory barriers to their production and helping local governments remove barriers that drive up housing costs. A key proposal involves allowing “middle housing”—buildings with less occupant density than large apartments but more than single-family homes—in areas traditionally restricted to single-family use.
Arguments in Favor of Reform
Increased Housing Supply and Improved Affordability
Allowing multi-family housing in previously single-family neighborhoods can help address housing shortages by maximizing the number of homes on each plot of land. Oregon’s House Bill 2001 (2019) required cities with over 10,000 residents to allow duplexes while even larger cities had to permit up to fourplexes on residential lots, opening opportunities for more diverse housing construction. Furthermore, a 2021 analysis in Washington County showed that while development varied based on market conditions, middle housing was financially feasible in many areas; expanding supply through zoning reform helps relieve pressure on prices and offers more options for moderate-income households.
Minimized Exclusionary Zoning
Single-family zoning has a legacy of racial and economic exclusion, often being used to prevent Black and Brown families from accessing certain neighborhoods. These patterns have had long-lasting consequences, including unequal access to high-quality public schools, limited proximity to grocery stores and fresh food, and disparities in infrastructure investment. Acknowledging this, Minneapolis became the first major U.S. city to eliminate single-family-only zoning through its 2040 plan, which aimed to reverse historic patterns of segregation by making neighborhoods more inclusive.
Aging-in-Place and Family Flexibility
Multi-unit housing provides flexible living arrangements that are increasingly important for aging populations and multigenerational families. Certain options, like accessory dwelling units (ADUs)—small, self-contained homes located on the same lot as a single-family house—along with duplexes and triplexes allow older adults to downsize while staying in their communities. ADUs in particular help people “age in place” by offering smaller, more accessible homes on the same property. Even more, they have helped increase the housing supply and provide “naturally affordable” rental housing with prices below market rates.
Alignment with Climate and Transit Goals
Research shows that higher-density housing near public transit supports environmental goals by reducing car dependency. For example, Oregon’s Transit and Housing Study highlighted how zoning changes can complement transit-oriented development by increasing housing options near transportation networks. Research from the National Academies further demonstrated that residential density near transit correlates with lower vehicle miles traveled and reduced greenhouse gas emissions. Reforming zoning with environmental planning in mind can be a valuable way to address both housing and climate-related issues.
Arguments Against Reform
Worsened Neighborhood Character
Many critics fear that multi-family zoning will negatively alter the appearance and feel of established neighborhoods. In Minneapolis, some residents opposed the 2040 Plan, claiming it would destroy the “charm” of their communities, cause overcrowding, and worsen traffic and parking. While such concerns vary by neighborhood, they reflect broader anxieties about rapid change and the potential mismatch between existing infrastructure and new development.
Potential for Displacement and Gentrification
Without affordability mandates or tenant protections, upzoning may push out existing residents by building high-end units that increase land values and rent prices. These concerns were raised by residents and lawmakers alike during legislative hearings regarding Oregon’s House Bill 2001. In addition, researchers at the Terner Center highlight that while zoning reform can be beneficial, it must be paired with planning and affordability tools to avoid reinforcing inequities.
Limited Uptake in Practice
Opponents of the policy point out that legalizing more housing types doesn’t guarantee they will be built. After Minneapolis enacted its 2040 Plan, only about 70 new duplexes or triplexes were built in the first year – far below expectations. Unfortunately, even when zoning reforms are passed, developers often face financial and regulatory barriers that limit the construction of new units. One of the major barriers involves infrastructure and permitting limitations. Upzoning increases demand for public infrastructure, including water systems, roads, and sewer lines. Thus, despite middle housing being financially feasible, its implementation has been delayed in Oregon because of permit limitations and misalignment with infrastructure planning.
Current Trends and Future Developments
In Oregon, the implementation of HB 2001 has led to a steady rise in middle housing permits in cities such as Eugene and Beaverton. State planners have continued to link zoning reforms with goals involving climate resilience and transit access, heightening the potential for sustainable housing and residential lifestyles. This is strengthened by decisions to tie federal funding to zoning and infrastructure coordination as a way to support sustainable reform. Minneapolis, after a brief legal setback, had its 2040 Plan reinstated by court order in 2024, allowing the city to move forward with efforts to increase housing options and reduce residential segregation.
Key Policy Design Questions
As policymakers across the country consider incentivizing middle housing options, they will likely need to consider the following questions:
- How can cities prevent displacement and gentrification when expanding zoning options?
- Can the current infrastructure handle the increased demand from higher-density housing?
- Should zoning reform include mandates or incentives to produce affordable units?
- How can these reforms be paired with transit and climate policy to meet sustainability goals?
Conclusion
Zoning reform that permits multi-family housing in single-family neighborhoods offers cities a promising way to expand their housing supply, support inclusive growth, and meet sustainability goals. However, its success depends on careful implementation. Oregon and Minneapolis offer valuable lessons for other cities considering similar policies; they have shown that legal changes alone are not enough. Effective reform requires coordination with infrastructure, affordability mandates, and clear community engagement.