Depth to Bedrock and the Formation of the Manhattan Skyline, 1890–1915

New York City historiography holds that Manhattan developed two business centers—downtown and midtown—because the bedrock is close to the surface at these locations, with a bedrock “valley” in between. This article is the first effort to measure the effect of depth to bedrock on construction costs and the location of skyscrapers. We find that while depth to bedrock had a modest effect on costs (up to 7 percent), it had relatively little influence on the location of skyscrapers. “Hour by hour the caissons reach down to the rock of the earth and hold the building to a turning planet.” Carl Sandburg, Skyscraper