Why San Francisco isn’t bigger

Large swaths of America’s cities were originally underwater. We stopped half a century ago, but there is plenty more land left to take.

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Some of America’s most famous land was reclaimed from the sea. The Lincoln Memorial, the World War II Memorial, and the Reflecting Pool all sit on earth reclaimed from Potomac River tidal flats in the early twentieth century. Treasure Island was built in San Francisco Bay for the 1939 Golden Gate International Exposition. Chicago’s Northerly Island was filled in from Lake Michigan to complete Daniel Burnham’s 1909 plan of the city.

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.

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.

Two explanations are commonly proposed for this: first, that the easy spots have already been reclaimed, and second, that improved transportation has made reclamation unnecessary since we can expand cities further inland instead. But neither of these matches the evidence. Other countries still reclaim land at enormous scale, under conditions at least as challenging as those in the United States. The transportation story was once plausible, but not any more. Transportation has stopped improving, and downtown land values have risen so much that reclamation costs would be dwarfed by the value of the land created.

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.

Have we run out of good spots?

A common explanation is that we simply ran out of good places to reclaim. According to this view, there used to be plenty of shallow, semi-dry plots available, but they’ve mostly been used up.

There are indeed a finite number of shallow bays near major cities, and since land is often raised in one area by dredging the bottom of the surrounding waters, land reclamation can eat into its own expansion opportunities. But even so, many countries have been adding land for centuries without running out of good options. China has the longest reclamation history of any nation, stretching back to the Tai Lake Basin in the fifth century BC. Low-lying wetlands along the Yangtze river were made suitable for building by using dams and drains. If the US hit the limit of suitable areas for land reclamation within two centuries, China would surely have long since run out, having begun the practice over two thousand years ago.

But China still leads the world in land reclamation, with close to 80 percent of all land reclaimed in the twenty-first century. Since 2000, Chinese cities of over one million people have reclaimed a land area equivalent to 39 Manhattans, with even more reclamation occurring outside city limits.

American history argues against this theory too: reclamation wasn’t confined to a few choice spots in the most valuable cities. It was common along both coasts, even in smaller cities like Charleston, Wilmington, and Portland.

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.

It is possible that the United States could eventually exhaust its opportunities for land reclamation. But given how much further other countries have gone and how much suitable coastline remains, that point is likely a long way off.

Has transportation made land reclamation unnecessary?

Another explanation is that land reclamation was replaced by transportation. When walking was the main mode of travel, cities faced tight spatial constraints. Boston began as a tiny peninsula of about two square miles. The city quickly outgrew its isthmus, but land to the south was too far for commuters to walk from. If Bostonians wanted to build close to the city center, they had to expand into the sea.

Other cities faced the same problem even where land was more abundant. In 1890, while Manhattan’s population was similar to today’s, there were still farmhouses beside Central Park, only six and a half miles north of Wall Street. The need to build within walking distance of the city center made northern Manhattan effectively unusable, justifying extensions to the southern tip. Even with plenty of dry land available, the city kept filling in riverbeds and marshland around the island. In all, over a quarter of Manhattan’s land was reclaimed before 1979.

Over time, however, land reclamation became less useful. Better transportation unlocked lots of greenfield land that was cheaper to develop than dredging up new land from the water, while the elevator unlocked brownfield land from the sky.

This abundance of new land within the commuting zone of cities was a cheaper substitute for reclaimed land. Boston’s Back Bay reclamation in the 1860s cost about $400,000 per acre in 2025 dollars. Although the state of Massachusetts ended up selling the land for a healthy profit, by the 1910s there were cheaper ways to unlock land within reach of the city center. If each of the 332 stations of New York’s 1913 subway extension connected a half-mile radius to the downtown, this form of land reclamation cost only $65,000 per acre in 2025 dollars, five to ten times less than land reclamation from the sea.

But this alternative source of land has proven difficult to extend indefinitely. First, while there may be land that we can access by expanding our cities outwards into virgin countryside, doing so is politically tricky in most countries, not least the United States. Adding more New York suburbs in New Jersey and Connecticut would mean a modern Robert Moses building more expressways through Manhattan.

Second, with enough population and economic growth, even the vast swaths of land accessible by modern transportation can eventually be filled. The edge of New York’s metropolitan area is already 40 miles from Midtown Manhattan at many points, over an hour’s commute. After rapid improvements in the twentieth century, transportation technology has stagnated. Average commute times have increased by a quarter since 1980, partly because cars haven’t grown much faster and partly because highway construction costs at least four times as much per mile as it did in 1960.

Finally, reclamation adds space near city centers, where land is far more valuable than at the suburban fringe. Cities are valuable because they concentrate economic activity, making it easier to find jobs, customers, and suppliers, and because they generate knowledge spillovers making everyone more productive. Better transportation increases their value by putting more workers, suppliers, and customers within reach. Crime and pollution pushed people out of city centers in America after World War II. But since 1990, this trend has reversed, and the value of land in city centers has grown quickly despite continuing suburban expansion.

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.

How reclamation went extinct

Neither explanation is convincing, especially where urban land values would plainly justify reclamation. But there is another problem: the explanations cannot easily account for the timing of land reclamation’s disappearance. A technological or geographic explanation would predict a slow and patchy decline, as different regions responded to different pressures at different speeds. But this is not what happened. In the 1970s, reclamation stopped virtually simultaneously everywhere in the country.

Of the 37 cities for which we can find data, every one reclaimed land more slowly after 1970, with many, such as Seattle and Chicago, slowing to zero. A few, including San Diego, Washington, and New York, do show some growth in land area after 1970. But most of this reflects changes in measurement or the completion of projects already underway.

The abruptness of the change shows up clearly in data on the amount of wetland that is lost per year. Most wetland loss is inland and agricultural, not the coastal urban reclamation we’re advocating. Still, the aggregate trend makes it clear that land reclamation ended suddenly around the 1970s. The annual rate of wetland loss in the 1960s was eight times higher than in the 1990s, and twenty times higher than in the 2010s.

In the 1970s, the United States passed a wave of new environmental laws, with perhaps the most far-reaching effects on land use in the country’s history: The National Environmental Policy Act of 1969 (known as NEPA), the Endangered Species Act of 1973, the Clean Water Act of 1972, the Marine Mammal Protection Act of 1972, the Resource Conservation and Recovery Act of 1976, and others. These laws hit the whole country at once, enormously raising the cost of reshaping the landscape, and are the real explanation for the end of American land reclamation.

Still in force, these laws largely regulate the federal government and not private development. But the moment a private project touches federal land, funding, or permits, it must comply with all of them. For land reclamation, NEPA is the most onerous.

NEPA requires covered projects to prepare a detailed report on the environmental impact of the proposed action and its alternatives. While NEPA itself sets no standards for how detailed these reports must be, decades of litigation have turned them into thousand-page behemoths that take years to produce. The environmental assessment for New York City’s congestion pricing plan, for example, is 900 pages long with 3,000 pages of appendices, despite the project requiring zero major construction. When potential harms are identified, agencies must undertake mitigation: buying and restoring 3,000 acres of panther habitat, say, or donating $16 million to conservation banks. In some cases, the project is simply blocked.

Land reclamation must always go through the NEPA procedure because the Clean Water Act requires a federal permit for any discharge of dredged material into waterways or wetlands, including the entire coast. Because land reclamation projects do have significant environmental effects, every project must either complete a full environmental impact statement or produce an environmental assessment with costly mitigation measures before receiving a permit. Environmental impact statements filed by the US Army Corps of Engineers, the agency that oversees the permits for land reclamation, take an average of six years to complete, and the mitigation measures often run into the hundreds of millions of dollars.

The Craney Island extension in Norfolk, Virginia is a useful illustration of how these laws complicate land reclamation. Craney Island is a four-square-mile rectangle of dirt and sand surrounded by dikes at the mouth of the Elizabeth river, built solely to store material dredged from Chesapeake Bay navigation channels. In 1997, Congress approved a study of the possibility of expanding the island to the east, extending the lifespan of the disposal area and adding a container shipping terminal to the Norfolk port.

By historical standards, this would have been an easy project: the original 2,500-acre Craney Island was built in just two years between 1956 and 1958. But because the extension involved discharging dredged material into US waters, it needed a Clean Water Act permit. The Army Corps’s environmental impact statement took nine years and ran to 1,400 pages.

Virginia’s environmental quality department then issued permits in 2010, three years after the environmental impact statement was published. After a decade of delays and budget uncertainty, the Corps changed its discharge plans in 2023, which required yet another supplemental environmental assessment. Twenty-eight years after the feasibility study began, almost nothing has been built. The project is expected to finish ‘on schedule’ in 2065.

Craney Island is not an isolated case. Land reclamation ground to a halt across the country after the major environmental laws passed in the 1970s. Very few US reclamation projects started later in the twentieth century, and no notable urban reclamation projects have taken place in the twenty-first.

Evidence for environmental law’s role in the end of American land reclamation can also be found in other countries. It declined abruptly in the 1970s and 1980s across the West. What western nations shared was the rise of powerful environmental movements hostile to reshaping the landscape.

Germany reclaimed over 80,000 acres from the marshy Wadden Sea before 1990. Tens of thousands more were planned, but fierce environmental opposition ended the practice in the late 1980s, turning the Wadden Sea into a national park and making wetlands protected areas. In the 1960s, France used reclamation to develop its Mediterranean coast into a world-class tourist destination, but environmental protection laws in the 1980s banned all construction within 100 meters of the shore.

In the early twentieth century, Canada reclaimed tens of thousands of acres of floodplain in British Columbia and the Maritimes, along with hundreds of acres of urban land in cities like Toronto, but large projects like these have stopped or greatly slowed due to environmental rules. In nineteenth-century Australia, hundreds of acres were reclaimed in Sydney Harbor, including the land under the Sydney Opera House, but twentieth-century environmental rules have prevented future expansion.

Even the Dutch, history’s most celebrated reclaimers, largely ceased the practice after the passing of their own environmental laws. From about 1917 to 1970, the Dutch undertook the largest reclamation project in history: the Zuiderzee Works, which expanded the Netherlands by five percent. The fastest phase, the 1927 Wieringermeer Polder, dammed and drained 50,000 acres in just three years. The 1957 Eastern Flevoland Polder then reclaimed nearly three times the area in less than eight years.

But only four of the five planned polders were filled. The fifth, the Markermeer, which was dammed and ready to drain in 1975, was never completed. It would have provided the closest land to Amsterdam, where house prices have risen 120 percent since 2010. In 1969, the Netherlands created a new approval process for large spatial planning projects similar to the NEPA. This process required extensive public consultation and referendums which, while not as explicitly environmental as NEPA, were still dominated by environmental concerns. While the debate dragged on, the 1979 European Birds Directive added another layer of environmental protection. Environmental groups campaigned to halt reclamation permanently and have the unfilled lake designated a Special Protection Area.

In response, the government eventually abandoned its land reclamation plan. In 1992, the Markerwaard was listed as a protection area, preventing any development on some of Europe’s most valuable water. (Some reclamation has resumed since 2014, but not for people: a €300-million, decades-long project is building swampy archipelagos in the lake as bird habitat).

Even the rare successes are instructive. The one major Dutch reclamation of the twenty-first century, an expansion of the port of Rotterdam called Maasvlakte 2, took eighteen years to complete, including an eleven-year planning and environmental compliance period before construction began. Its environmental review alone ran to some six thousand pages.

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 multiple airports, port facilities, and residential areas built on reclaimed land.

Land reclamation has always faced obstacles, and the story of its historical fortunes is not simple. But the weight of the evidence points in a clear direction. In America, as across the West, land isn’t reclaimed today because of barriers of geography or technology, but because 1970s environmental regulations made it prohibitively expensive and slow.

The wrong solution for an old problem

Reclamation would be feasible and profitable in the West today if some environmental laws were changed. But those laws were passed to solve real problems. So is it worth bringing land reclamation back?

The postwar state had incredible power to act unilaterally and grade its own work. Robert Moses could demolish entire neighborhoods for expressways without accountability; urban renewal programs replaced them with awful housing blocks; the Cuyahoga River caught fire from wanton industrial pollution; the interstate highway system demolished half a million homes to make way for highways through urban areas; and indeed land reclamation was sometimes responsible for the loss of valuable wetlands. These excesses understandably created fear of unchecked development.

Environmental laws provided necessary curbs, but since the 1970s, the costs of compliance have grown as NEPA reports expanded from ten pages to thousands and spurred half a century of expensive litigation.

Simultaneously, the value of foregone construction has never been higher. Real housing prices are at least five times higher today than in 1970 in New York, San Francisco, Boston, and LA, and three times higher across the country as a whole. Land reclamation may be the most striking casualty of 1970s environmental law. Land reclamation makes housing cheaper, cities more productive, and transportation networks more efficient. It also addresses twenty-first-century environmental challenges: city dwellers produce far less carbon per person than suburbanites, and reclaimed land can make coastal cities more resilient to natural disasters.

Despite the environmental costs, there are many places in the country where the benefits of land reclamation are too great to ignore, in particular in and around our biggest cities. In some cases, the environmental benefits of bringing more people into dense, efficient cities where they have far lower emissions per capita may outweigh the loss of aquatic habitat all on its own, leaving the direct benefits of more land as pure reward.

Land reclamation is not the solution to everything, but there’s no good reason we should be worse at land reclamation than we were 150 years ago. There is plenty of land that is easy to reclaim and plenty of areas where the value of land is far greater than the cost of acquiring it. The benefits of more land in our most productive cities are large enough to justify the effort of reforming the laws that currently prevent it. Let’s make more land!

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Zigmund Forrest is an independent researcher. Maxwell Tabarrok is a graduate student at Harvard University.

Artwork by Filip Setmanuk.