The War on Roommates: Why Is Sharing a House Illegal? Author: Alex Tabarrok Date: August 29, 2025 Category: Economics --- Summary This article addresses the puzzling and counterproductive legal restrictions on shared housing and why sharing a house with unrelated roommates is often illegal or heavily regulated in many U.S. cities. Key Points Historically, single-room occupancy (SRO) units or boarding houses were common, providing low-cost housing options where residents shared kitchens and bathrooms. These units occupied about 10% of rental units in major U.S. cities by 1950. Over the mid-20th century, urban zoning and building laws changed to restrict or eliminate SROs through: Single-family zoning laws forbidding multiple unrelated individuals to share a home. Occupancy limits capping the number of unrelated people living together. Requirements for every room to have a private bathroom. Rules outlawing shared kitchens. Mandates for parking spaces for every resident. These regulations effectively made sharing housing illegal or difficult, causing the decline and disappearance of many affordable housing units. The decline in SRO housing coincided with a rise in homelessness, which previously had been rare after the Great Depression until the late 1970s. Pew Research Study Highlights Pew published a detailed analysis showing the decline of SROs was due largely to changes in laws and public opposition, not just market forces. The report recommends simple reforms, such as: Allowing unrelated individuals to share houses equally, without restrictions that favor families. Repealing occupancy laws limiting unrelated residents in one household. States like Iowa, Oregon, and Colorado passed legislation in recent years to overturn local bans on house-sharing, showing bipartisan support for reform. Broader Implications and Challenges Many comments and experts note that cultural expectations, personal preferences, and social conditions affect the viability and desirability of shared housing. Issues often raised include: Maintenance and tenant behavior concerns, especially with vulnerable populations (e.g., substance abuse, property damage). Changing social norms, where having roommates beyond youth is stigmatized. Economic incentives, where landlords and tenants often prefer traditional apartments or single-family arrangements. Legal challenges, such as difficulties in evicting problematic tenants or liability risks for landlords. Some commenters highlight historical and neurological factors: Lead poisoning in the 20th century correlated with social problems, reducing suitability for high-density group living. New research on lithium deficiencies and reduced lead exposure suggests potential for a more sociable generation capable of shared living. The author and commenters agree many problems stem from policies by "busybody" regulators who prevent efficient use of property. Additional Insights from Comments Shared housing and SROs are often concentrated near college campuses or urban centers, with more flexibility in some jurisdictions. The demand for shared housing may be smaller than assumed; many still prefer detached single-family homes when affordable. Neighborhood opposition ("NIMBYism") and stigma against poor people contribute to restrictive zoning. Some argue homelessness and housing affordability are more influenced by: Concentration of wealth and high salaries in tech hubs. Legal and regulatory environments that discourage flexible housing solutions. Challenges dealing with drug abuse and social dysfunction among the homeless. Alternative housing models, like "tiny homes for the homeless," illustrate efforts toward low-cost, shared accommodations. --- Conclusion The illegality or heavy restriction of sharing homes with unrelated