In total, around eight percent of the land in America’s major coastal cities was underwater in the 1890s and has since been reclaimed. This includes the land under several major airports, like Newark, Logan, and SFO, as well as neighborhoods like the Financial District in San Francisco, the Back Bay in Boston, and Camden in Philadelphia. Some cities, like Boston and Charleston, have doubled in size by reclaiming land.
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Today, reclamation should be more common than ever. Land values in some cities are thirty times what they were in 1950, and high-tide flooding is four to eight times as frequent. Reclamation could extend and protect our coastal cities as it has for centuries. But rather than reclaim more land, we have virtually ceased to reclaim any at all. Since the completion of Battery Park City in 1976, there has not been a single major urban land reclamation project in the United States and only a handful of port expansions.
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The timing points to a third explanation. Reclamation stopped abruptly in the 1970s when a wave of environmental regulations made it enormously expensive to reshape the landscape. And it halted at the same time in every other country that passed similar laws.
If the legal barriers to reclamation were lifted, we could build hundreds of thousands of new homes near the centers of our most valuable cities. We could build new airports to refresh ailing transportation infrastructure, and we could protect low-lying coastal areas from sea level rise. The disappearance of land reclamation is a choice that we have the power to undo.
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Hundreds of square miles of water near major American cities are shallow enough to reclaim easily. When Boston’s Back Bay was filled in the late-nineteenth century, it had an average depth of 20 feet. Two thirds of the San Francisco Bay is shallower than this. The South Bay, adjoining Silicon Valley, is less than six feet deep. Outside the main navigation channels, most of New York harbor is less than ten feet deep. Almost all of the water between Miami and Miami Beach, and along the shelf extending south to Key West, is also less than ten feet deep. All of these could be candidates for reclamation.
Nor is depth a hard limit if land values are high enough. Monaco’s recent Mareterra project expanded the country’s land area by three percent by dredging down to 164 feet.
Soil and rock conditions also matter, but much of the American coastline has better conditions than sites where reclamation has already succeeded. Singapore’s Jurong Island is a massive industrial zone created on land reclaimed between 1995 and 2009. The water was more than 50 feet deep and atop another 50 feet of soft marine clay, which settles more than other materials under pressure. To reclaim the land, these layers had to be threaded with long plastic tubes to allow drainage and loaded with a large, heavy quantity of extra soil.
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Today, downtown land values are high enough to justify reclamation costs even in places where suburban land is plentiful. In 1955, the California Division of Water Resources estimated that reclaiming 23,000 acres of land on the west side of the San Francisco Bay would cost about $330,000 per acre in 2025 dollars. Today, the cost of an acre of single-family-zoned land in San Francisco County averages $24 million, more than 70 times the estimated reclamation cost. Even the cheapest county in the Bay Area exceeds $330,000 per acre.
Despite the space opened up by cars, trains, and buses, America’s biggest cities face a massive land shortage. Even as the transportation explanation has weakened, reclamation hasn’t returned. Boston’s Back Bay reclamation was profitable when land sold for the equivalent of $40 per square foot. Land in major cities today sells for ten to a hundred times that, and dredging capacity has grown nearly tenfold since 1950. Yet urban reclamation has disappeared even in the most land-constrained cities in the country.
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Reclamation has continued only in countries where environmental regulation is less onerous, like China, Singapore, and Japan. China has reclaimed over 5,000 square kilometers in the first two decades of this century, including a new city of 500,000 outside of Shanghai, and Singapore has expanded its territory by over a quarter since 1975.
Japan does have high environmental standards and a NEPA-style law requiring environmental impact reports. But Japan’s system has two advantages: clear numeric thresholds for when reports are required and courts that make it harder to overturn agency decisions. Japanese infrastructure projects don’t need the defense against legal challenges that make Western projects take decades. The result is abundant housing and infrastructure, including multipleairports, port facilities, and residential areas built on reclaimed land.
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