Bedrock Depth and the Formation of the Manhattan Skyline, 1890-1915

Skyscrapers in Manhattan must be anchored to bedrock to prevent (possibly uneven) settling; this can potentially increase construction costs if the bedrock lies deep below the surface. The conventional wisdom holds that Manhattan developed two business centers—downtown and midtown—because bedrock is close to the surface in these locations, with a bedrock "valley" deep below the surface in between. We measure the effects of building costs associated with bedrock depths, relative to other important economic variables in the location of early Manhattan skyscrapers. We find that bedrock depths had very little influence on the creation of separate business districts; rather its poly-centric development was due to residential and manufacturing patterns, and public transportation hubs. We do find evidence, however, that bedrock depths influenced the placement of skyscrapers within business districts.