Unused Floor Area Ratio and Skyscraper Development in Manhattan

Yuanhao Wu

Keywords: Manhattan / Floor Area Ratio (FAR) / Zoning / ArcGIS Pro / Mapbox / Urban Development

Overview

Manhattan’s skyline is constantly evolving, reshaped by zoning regulations, air rights transfers, and the city’s relentless drive toward vertical growth. This project explores how underutilized Floor Area Ratio (FAR) and transferable development rights influence where new skyscrapers emerge across Manhattan.

By combining zoning and building datasets with spatial analytics, I mapped how unbuilt zoning capacity, expressed as Unused FAR × Lot Area, translates into real-world construction patterns. The results reveal a clear spatial logic behind the city’s vertical expansion: neighborhoods with large reserves of unused FAR, such as Lower Manhattan and Hell’s Kitchen–Columbus Circle, are also where high-rise residential growth has been most active in recent years.

This study provides a data-driven view of how zoning potential shapes the skyline, offering insight into the hidden development capacity embedded in Manhattan’s built environment.

FAR = Total Building Floor Area / Total Plot Area

Methodology

Using MapPLUTO zoning data from the New York City Department of City Planning, I filtered all zoning lots within Manhattan to identify those with residential components. For each lot, I calculated Unused FAR = Max Residential FAR − Built Residential FAR to measure development potential. To better quantify this capacity, I introduced a derived variable, Unused FAR × Lot Area, representing the total amount of unbuilt space available for potential residential expansion.
The dataset was processed in ArcGIS Pro and Python to clean attributes, compute metrics, and visualize spatial patterns. A Hot Spot Analysis (Getis-Ord Gi*) was conducted to identify statistically significant clusters of zoning lots with high concentrations of unused development rights. These clusters reveal where zoning potential and transferable air rights are most densely concentrated.
Next, I incorporated building data to identify new residential developments across Manhattan. Buildings constructed or renovated after 2015 were filtered and categorized by completion period, while those exceeding 40 floors were defined as skyscrapers. Finally, using Mapbox, I overlaid the distribution of these skyscrapers on top of the unused FAR clusters, uncovering how zoning capacity translates into physical growth and visualizing the spatial alignment between development potential and actual construction.

Findings

- Identifying Underutilized FAR in Manhattan

To begin the analysis, I filtered all zoning lots within Manhattan from the NYC MapPLUTO dataset and focused on those designated for residential use. Areas with underutilized Floor Area Ratio (FAR) were defined as zoning lots where the built residential FAR is lower than the maximum permitted FAR, indicating potential for further vertical development.
To quantify this development potential, I introduced two new variables:

Unused FAR, calculated as Maximum Residential FAR − Built Residential FAR;
Unused Area, defined as Unused FAR × Lot Area, representing the total unbuilt floor area available for potential residential construction.

Using ArcGIS Pro, I performed a Hot Spot Analysis (Getis-Ord Gi*) to identify statistically significant clusters of zoning lots with large amounts of unused residential area. These hot spots highlight where zoning capacity is most concentrated and where future skyscraper development is more likely to occur.

It turns out that

Out of 42,127 residential zoning lots in Manhattan, 23,894 exhibit underutilized residential FAR.
Large reserves of unused FAR are concentrated in Lower Manhattan and Hell’s Kitchen–Columbus Circle. These areas serve as key examples of how zoning flexibility and redevelopment potential shape the city’s evolving skyline.

- Skyscraper Distribution and Spatial Correlation
Building upon the analysis of underutilized FAR, I next examined how new residential developments align with areas of high redevelopment potential. From the same MapPLUTO dataset, I identified all zoning lots containing buildings constructed or renovated after 2015, with a subset highlighting those completed after 2020. These buildings were categorized by construction period and visualized in Mapbox using distinct color symbology to reflect different development phases.
To isolate large-scale vertical growth, I filtered buildings exceeding 40 floors, defining them as skyscrapers. Because Mapbox imposes limits on the number of displayable layers, I adopted a heatmap visualization to represent their spatial distribution while maintaining map clarity and performance.
Finally, I overlaid the skyscraper heatmap onto the Hot Spot Analysis results from the previous section.

The spatial comparison reveals a clear pattern: new skyscrapers tend to cluster in neighborhoods with high concentrations of unused residential FAR. Notably, these clusters emerge around Lower Manhattan, particularly the Financial District and Lower East Side, as well as the Hell’s Kitchen–Columbus Circle corridor.

This alignment reinforces the hypothesis that

Transferable air rights and zoning flexibility play a key role in driving high-rise construction across Manhattan’s skyline.

Reflection

The study illustrates how zoning flexibility and transferable development rights directly shape Manhattan’s vertical density. Areas with large amounts of unused FAR tend to attract new high-rise developments, reinforcing spatial inequalities in growth and redevelopment potential. Understanding this pattern offers insight into the broader relationship between zoning policy, urban form, and gentrification, highlighting how development rights markets can transform the skyline while reshaping neighborhood dynamics.

Future Work