Historian Michael Glass describes how informal housing units came to be in the postwar suburbs:

Yes, this was a major surprise during my research. While scanning through microfilm reels of local newspapers, I kept coming across exposés of “illegal apartments,” that is, single-family homes illegally converted for multifamily occupancy. This took many forms: owners might rent out the basement, convert the garage into a dwelling, or wall off the attic as a separate apartment. Urban planners conducted comprehensive studies, and they estimated that by the 1970s between 10 and 20 percent of the single-family homes had been subdivided. A truly astounding statistic! 

In addition to being exclusionary and costly, the postwar suburban development model was completely unsustainable. Today the housing stock in Nassau County consists almost entirely of single-family dwellings. But people in the suburbs also needed cheap rentals, especially low-income families, young singles, divorced couples, retirees, and undocumented immigrants. Because zoning prohibited multifamily housing in most places, homeowners and landlords met these needs by converting single-family homes into apartments. 

The apartments were hidden, but certainly not a secret. Local officials absolutely knew the subdivisions were happening, and they let it continue because the informal apartments were meeting important housing needs. What I take from scholars of informal housing in the Global South – folks like Ananya Roy and Raquel Rolnick – is that turning a blind eye is itself a policy choice. It’s a way for government officials to manage housing needs in a context of scarcity. 

My basic argument is that informal apartments became the tacit solution to the affordable housing crisis. It helped resolve contradictions: local officials could simultaneously declare their opposition to new apartment construction while continuing to quietly tolerate informal units. 

People needed housing in the growing suburbs, homeowners adapted their properties, and local officials responded by not doing much. I wonder how much the lack of local reaction discovered was due to:

1. The actual need for housing. How many units were needed in the postwar decades, particularly in comparison to today? Even as suburbs were growing rapidly, how much would local officials admit that even more housing was needed?
2. The reference in the quote above to apartments is interesting as many suburban communities did consistently resist apartments because this might lead to different kinds of residents and affect the character and property values of nearby single-family homes. Informal housing is preferable to apartments until when?
3. What happened when local residents complained about informal units? Say a resident suggests their neighbor has created an informal housing unit in violation of local regulations. How did local officials respond given #1 and #2 above? The quote above refers to media exposes so there must have been some local responses.

This might fit into a bigger story of suburban residents who since World War Two have used their homes and properties in ways that go against local regulations or what was expected. The idea of property rights is pretty important in many suburbs but so is the impulse to not have one’s property and housing values threatened by nearby land uses.