Mayor Adams, Build a Bigger Manhattan

On Jan. 1, 2022, Eric Adams was sworn in as New York’s 110th mayor. He is now in charge of the city’s response to big, and growing, problems. One is a housing affordability crisis. Another concerns the ravages of climate change: sea level rise, flooding and storm surges.

There is a way to help tackle both issues in one bold policy stroke: expand Manhattan Island into the harbor.

Last September, after witnessing unprecedented flooding from the remnants of Hurricane Ida, Mr. Adams said that it was “a real wake-up call to all of us how we must understand how this climate change is impacting us.” This realization should spur him to pursue aggressive measures to mitigate climate change’s devastation.

Both Mayors Bill de Blasio and Michael Bloomberg offered climate-change plans that included extending the shoreline along the East River in Lower Manhattan. But these proposals, while admirable, would be small steps and would hardly make a dent with problems of such big scale.

This new proposal offers significant protection against surges while also creating new housing. To do this, it extends Manhattan into New York Harbor by 1,760 acres. This landfill development, like many others in the city’s past, would reshape the southern Manhattan shoreline. We can call the created area New Mannahatta (referring to the name the Lenape gave to Manhattan).

A neighborhood of that size is bigger than the Upper West Side (Community District 7), which comprises 1,220 acres. Imagine replicating from scratch a diverse neighborhood that contains housing in all shapes and sizes, from traditional brownstones to five-story apartment buildings to high-rise towers. If New Mannahatta is built with a density and style similar to the Upper West Side’s, it could have nearly 180,000 new housing units.

Housing

In 2014, Mayor de Blasio announced an affordable housing plan that would build or preserve 200,000 affordable units. Despite this, rents continued to rise because construction did not keep pace with population and income growth. To give a sense of the scale, from 2010 to 2018, 171,000 units of housing were constructed, enough to accommodate about 417,000 people. Yet in the same period, the city’s population grew by nearly 500,000.

The Covid pandemic put a temporary damper on New York City real estate, but its impact is waning, and the affordability crisis has renewed itself. Rents are returning to their prepandemic levels. Mayor Adams has provided his vision for affordable housing, which includes incentivizing more construction throughout the five boroughs. New Mannahatta offers the possibility to realize the goal of adding a significant number of new units, many of which can be made affordable for low-income households.

Storm Surges

Creating land in the harbor would also help New York City fortify itself against climate change. The new community would push currently vulnerable places like Wall and Broad Streets further inland, and the peninsula can be designed with specific protections around its coastline to buffer itself and the rest of the city from flooding. In particular, wetlands ecologies around the shorelines would absorb surges. Building the land at a higher elevation would further improve its protective ability, and the new peninsula could recreate historic ecologies and erect environmental and ecological research centers dedicated to improving the quality of New York’s natural world.

Economic Feasibility

One of the benefits of creating this new neighborhood is that it can pay for itself through sales or long-term land leases. Using the Upper West Side as a model, in 2019, average building sales were around $1,500 per square foot, while average citywide building construction costs were about $500 per square foot. That leaves the rest for producing the land and infrastructure, including expanded subway lines. New ferry routes can be created along the shorelines, which would aid in the city’s broader plan of increasing ferry usage. If managed wisely, the project could even turn a profit, especially if money comes from the new federal infrastructure bill. Once the properties were completed, the city would receive new real estate tax income. In 2017, the Upper West Side, for example, contributed about $1.4 billion to the city coffers.

Big Thinking in the Big Apple

New York was once a city of big projects like the Brooklyn Bridge, the subway system and the 92-acre Battery Park City (largely spared the flooding from Hurricane Sandy in 2012). In these times of peril, big thinking is necessary.

Mayor Adams has a chance to create a legacy of making New York safer and more affordable. New Mannahatta can help ensure that the city thrives in the 21st century.

Jason M. Barr (@JasonBarrRU), a professor of economics at Rutgers University-Newark, is the author of “Building the Skyline: The Birth and Growth of Manhattan’s Skyscrapers” and the Skynomics Blog.

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