Mapping data can help understand trends and leverage them for future strategy and business opportunities. Here, this historical look at the types of construction happening in major metros during the past few decades gives us a sense of how densification is shaking up suburbs.

In “The Great American Single-Family Home Problem,” New York Times reporter Conor Dougherty drives home the point that the high cost of housing in America’s expensive coastal cities can be addressed by densifying the suburban landscape. At first glance this may seem obvious; combatting price appreciation calls for building more homes, and better to do so through infill than by exacerbating sprawl. But the notion of densifying the suburban landscape is a more radical departure from the status quo than it may seem.

In the past, virtually every patch of land in the metropolitan U.S. continually sprouted new housing, but this is no longer the case. In recent decades, residential construction has become increasingly confined to the periphery of American metro areas, while a growing swath of the interior has fallen dormant and produces new homes at a negligible pace. At the same time, a tiny fraction of the land area, scattered in small pockets throughout the metropolitan landscape, is responsible for a growing share of new home production, primarily in large multifamily structures. I refer to this increasingly spiky new pattern of housing production as “pockets of dense construction in a dormant suburban interior.”

The story is best told through maps
The following map colors the residentially developed footprint of the Los Angeles metro area as of 1960 according to the dominant type of new housing built there during the 1940s and ‘50s. It distinguishes between single-family homes in light blue, 2 to 49 unit structures in orange, and 50+ unit structures in red, and assigns each Census tract a color based on the type of housing that accounted for the most new homes during the period.

The map reserves an additional color, dark blue, for areas that produced no new housing at all, or that produced it at a negligible pace, defined as less than 0.1 new homes per acre per decade. This pace is equivalent to less than one new home per acre per century, which means that transitioning a neighborhood from a stereotypical suburban density of 4 homes per acre to a borderline walkable one of 10 homes per acre at this rate would take more than 600 years.

In the 1940s and ‘50s the map was mostly light blue, indicating that the vast majority of the metro area’s developed footprint was producing new housing at a meaningful pace, mostly but not exclusively in the form of single-family homes. Although a number of areas show up in orange, implying a local abundance of moderately sized multifamily structures, only a tiny fraction show up in red, and even fewer show up in dark blue.

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