From Island of Hills to Cartesian Flatland? Using GIS to Assess Topographical Change in New York City, 1819–1999*

Abstract

Historical geographic information systems (GIS) scholarship has provided important insights into a broad spectrum of historical questions in recent years. This article contributes to the emerging field of historical GIS by employing map algebra and transect analysis to quantitatively assess topographical change resulting from rapid urban growth in New York City since the first quarter of the nineteenth century. These methodological techniques enable a systematic comparison of Manhattan's historical and contemporary topography through a spatial analysis of various topographic metrics, including the extent of positive and negative elevation change, shifts in elevation range, the percentage of geographic area that experienced elevation changes, and the estimated volume of Earth added to and removed from particular areas within the study site. The results indicate that there were more valleys filled than hills leveled on Manhattan's East Side, whereas the reverse was the case on the West Side. The West Side, however, experienced considerably more topographic changes than its eastern counterpart, in large part due to the former's more rugged terrain. Overall, the evidence suggests that although Manhattan's topography has been radically transformed in certain respects, the broader spatial pattern of topographic variation has remained largely constant. These findings, therefore, can be used to support competing narrative claims concerning the significance of the topographical transformations that resulted from the urbanization process in New York City.