Introduction

The Central American Sea-Level Canal and the Environmental History of Unbuilt Megaprojects

THE ATLANTIC-PACIFIC Central American sea-level canal was a spectacular failure. The famed French engineer of the Suez Canal, Ferdinand de Lesseps, destroyed his career and the lives of twenty-five thousand workers by insisting he could excavate across the mountainous Panamanian isthmus in the 1880s. Learning from his mistakes, the Americans succeeded in the early 1900s by taming the tropical insect-borne diseases and building an ingenious “bridge of water” with a dam and locks that lift ships eighty-five feet above sea level. However, the world-changing Panama Canal appeared more and more obsolescent and vulnerable as ship size and military airpower increased, leading its postwar operators to dust off old plans for a means of connecting the seas without any impediments. Nuclear weapons designers thought they had discovered the key to unlocking the canal in the form of peaceful nuclear explosives (PNEs), and to that end the U.S. government spent hundreds of millions of dollars and thirteen years considering the question of atomic excavation. And yet, when a presidential commission announced in 1970 that it had ruled out PNEs in favor of ordinary construction methods, critics from both the right and the left in essence declared, “told you so.”

That in a nutshell is the conventional story of the Atlantic-Pacific sea-level canal, a megaproject that failed to make the transition from idea to reality and thereby enter the pantheon of monumental civil engineering works. Devoting historiographical attention to such a nonevent might seem counterproductive.1 But over the last two decades scholars have produced insightful technoscientific and diplomatic histories of the nuclear canal proposal (de Lesseps’s project has received more attention, though mainly as a counterpoint to the American success). Scholarly studies of the nuclear canal have enriched our understanding of Cold War–era mentalities and geopolitical relations by addressing it in the context of Project Plowshare, the 1957–77 U.S. initiative to apply nuclear energy to earthmoving and other nonmilitary pursuits.2 The “Panatomic” proposal sheds light not only on the hubris and tenacity of Plowshare, but also the arrogance and persistence of U.S. imperialism in Panama, which lasted from 1903 (when the United States helped engineer a revolt against Colombia) to 1999 (when Panama assumed full sovereignty over the waterway and surrounding zone).3

This book examines the nuclear canal in a different context, as one of several science-based iterations of an anticipated infrastructural future that began with the founder of environmental science, Alexander von Humboldt, and stretched to the turn of the millennium, almost three decades after the demise of Plowshare. Although the sea-level ship canal did not come to pass, as a proposal it served important political and scientific purposes during different eras. During the 1950s and 1960s, it enabled three U.S. presidents to address the increasingly problematic Panama Canal Zone, the colonialistic enclave surrounding the original waterway, and during the 1970s and 1980s, it offered new visions for dealing with the oil crisis. Throughout the most serious period of governmental attention, from 1965–70, the plan provided opportunities for producing new knowledge to resolve the burning question of whether detonating buried thermonuclear bombs to excavate the “very deep cuts required by an interoceanic canal” was technically feasible.4 The U.S. government’s then lack of legal requirements for assessing environmental impacts, and its narrow definition of the kinds of information, expertise, and authoritative capacity deemed most relevant to this task, in turn generated high-profile debates within the scientific community over the project’s nonradioecological, nonanthropocentric risks. After officials ruled out nuclear construction methods—an outcome that was never inevitable—ecological concerns about how the sea-level canal and other maritime transportation complexes might affect the biological integrity of the oceans continued to circulate in the policy realm in ways that still resonate today.

In other words, as science and technology studies scholars would say, the sea-level canal proposal performed different kinds of work for different historical actors, and vice versa.5 Dismissing it as a failed scheme unworthy of historiographical attention prevents us from considering the political, cultural, and epistemological processes that went into constructing the seaway as an innovative diplomatic solution, an exciting research opportunity, a superior hydrocarbon highway, or a serious ecological threat. These processes highlight themes of broader relevance to environmental history and the history of science and technology. The controversies over the nuclear and nonnuclear phases of the sea-level canal signify the disintegration of a powerful technocratic worldview that permeated U.S. environmental management from the construction of the original Panama Canal until the rise of the modern environmental movement.

Deep Cut uses the Central American seaway proposal to address specific elements and consequences of this revolutionary shift, especially the changing roles of environmental expertise and state-sponsored preliminary environmental impact assessment, and the historical contingencies of infrastructural decision-making. More broadly, this book contributes to an emerging literature addressing the environmental, scientific, and political histories and legacies of unbuilt megaprojects.

AS SUGGESTED BY a small but growing number of researchers from diverse fields, the history of planned but unrealized projects—from single buildings to regional development endeavors—deserves much greater attention. One of the first studies of “unbuiltism” appeared over forty years ago. An art historian coined this odd word in the introductory essay of Unbuilt America, a book featuring dozens of salvaged drawings and descriptions uncovered by two artists from architectural firms, libraries, and private collections in the 1970s.6 According to the authors, only one other such work dealing “exclusively with the unbuilt as a phenomenon” had ever appeared, and that was in 1925.7 Unbuilt America focuses on buildings and monuments, but the reasons proffered for their lack of execution apply as well to larger-scale architectural, engineering, and landscape projects. Visions of the built environment fail to take form for many reasons, including lack of funding, bureaucratic inertia, technical infeasibility, and community resistance. The book did not unleash a groundswell of academic or popular interest in unbuiltism, but its time has come. A recent set of coffee-table books devoted to never-built structures envisioned for Los Angeles and New York have become best sellers and spawned Kickstarter-funded museum exhibits meant to inspire viewers to consider what might have been and what might be different for the human-dominated landscapes of the future.8

The curators of the Never Built series hail from the world of architecture, but more deeply contextualized case studies of unrealized large-scale projects have emerged from across the environmental humanities.9 Cultural historian Kathryn Oberdeck coined the phrase “unbuilt environment” in a 2005 essay about the value of archives as conservatories of unrealized urban visions.10 Moreover, in the words of geographer Michael Heffernan, “Unsuccessful initiatives, especially controversial and long-running ones, tend to leave an archival legacy that is more complex and extensive than realized projects. Failures allow the historian to chart the limits of our faith in science and technology.” Analysis of the private and public evidence of grandiose ventures that never came about can also shed light on imperialist and modernist attitudes that continued to influence development thinking long afterward. These are important points of Heffernan’s pioneering studies of late nineteenth-century French colonial plans to transform the Sahara Desert into a vast inland sea and railway network that would fuel the development of northern Africa.11

Another never-built Eurocentric macroengineering project with rich insights for the history of science, technology, and human-environment relations was Atlantropa. From 1927 until his death in 1952, German architect Herman Sörgel sought to overcome European fears of energy shortages and cultural decline by damming the Mediterranean to generate hydroelectricity and lower the sea enough to create a new continent connecting Europe and Africa. In his vision, climate engineering would stave off desertification, thereby ensuring healthful conditions for Atlantropa’s imperialist European communities and industries. The megaproject’s scale, complexity, and cost undermined its feasibility, but its failure was not preordained. The idea circulated in German academic and popular media for over two decades, revealing “lesser-known environmental issues and fears in the first half of the twentieth century that—in altered form—are still with us today.” Atlantropa elucidates “the still-understudied history of the unrealized utopian projects of high modernism.”12

High modernism refers to a philosophy underpinning massive projects of the twentieth century that came to fruition but otherwise failed to achieve their lofty goals of improving the human condition, in the words of political scientist and anthropologist James Scott. Scott’s influential analysis uses cases such as the Soviet collectivization of agriculture and the Brazilian construction of a new capital city in the Amazon rainforest to demonstrate how high modernists mobilized science and technology to advance progress, yet wound up causing great ecological and social harm by privileging centralized technocratic expertise and rigid centralized directives above local knowledge and needs.13

The most notorious high-modernist projects have taken place in authoritarian societies capable of crushing dissent, but democratic governments have also promoted problematic large-scale agricultural, industrial, and urban development projects despite fierce local resistance. A revelatory example is the St. Lawrence Seaway, the U.S.-Canadian transportation and hydroelectricity complex that submerged several villages and displaced 6,500 citizens. Historian Daniel Macfarlane uses the concept of “negotiated high modernism” to show how U.S. and Canadian officials strategically used the public planning process to overcome opposition from stakeholders who did not stand to benefit. Decision makers had to “adapt, negotiate, and manufacture consent in order to achieve a veneer of democratic legitimacy” to actualize their vision.14 This concept is also useful for examining technocratic ventures that did not pass the regulatory policy-making processes of liberal democracies.

One of the ultimate high-modernist enterprises that did not advance beyond the experimental stage, and to which the concept of negotiated high modernism applies, was the aforementioned Project Plowshare program of the U.S. Atomic Energy Commission (the Soviet Union operated its own such program for even longer). Starting in 1957, Plowshare officials convinced Congress that investing in PNE feasibility studies would reap huge dividends in the form of cost-effective transportation infrastructure (harbors, roads, and canals), energy sources (especially the extraction of oil and gas from shale and tar sands), medical breakthroughs (via the production of isotopes), and weather modification.15 As for the question of releasing radioactivity into the environment, Plowshare scientists and engineers, most of whom worked at the Lawrence Radiation Laboratory at the University of California at Livermore, believed they could develop what they called clean explosives. Because a PNE consisted of a thermonuclear device with a fission trigger, the smaller the amount of harmful radionuclides released via the fission process and the deeper the device was buried, the less the radiation hazard. However, placing a PNE too far underground would reduce its effectiveness for earthmoving purposes. Figuring out the optimal combinations of such variables as burial depth, percentage of vented radiation, and the number of explosives needed for a given goal required extensive testing. The Atomic Energy Commission (AEC) conducted twenty-seven experimental explosions for Plowshare, primarily at the Nevada Test Site, from 1961 to 1973. Each one required presidential permission and intensive calculating of political risks, especially after the Limited Nuclear Test Ban Treaty of 1963 banned countries conducting atomic experiments from releasing radioactive debris across national borders.

Today the idea of detonating buried hydrogen bombs to excavate a waterway or frack natural gas seems absurd if not “mildly deranged.”16 Plowshare’s most famous supporter was the physicist Edward Teller, whose uncompromising advocacy for the hydrogen bomb might have inspired the 1964 movie Dr. Strangelove.17 Likewise, Teller’s plans to reshape the earth with PNEs now make for compelling clickbait; recent media accounts of Plowshare feature adjectives such as bizarre, crazy, insane, madcap, outlandish, and wacky.18

But for a confident, technocratic society seeking to accelerate modernity, PNEs were anything but bizarre—rather, they held the promise of harnessing knowledge to enhance the quality of life at bargain prices. Federal officials were not required to take what we would now call environmental costs into consideration, which helps explain why for them nuclear excavation appeared much less expensive than conventional methods. As Teller and his allies argued, atomic excavation would not only save money but also reduce the number of worker injuries and deaths caused by massive construction projects. For such reasons Plowshare advocates considered themselves “the personification of progress and modernity.”19 For scholars of high modernism, of the Cold War, and of the history of science, technology, and the environment, Project Plowshare offers a window into a worldview that revered technoscience to the point of assuming that serious environmental health risks could be contained and that dissent on such grounds was irrational.

Like many midcentury Americans, Plowshare’s powerful sponsors in Congress and the executive branch held great faith in the power of science and technology to solve social and political problems. At the same time, U.S. decision makers operated in the context of checks and balances. However imperfectly, unevenly, and inconsistently, democratic governing systems provide opportunities for challenge and change. Examining how proponents of Plowshare dealt with outsiders asking tough environmental and public health questions shines light on the evolving political role of scientific expertise and dissent vis-à-vis environmental impact assessment in the mid-to-late twentieth century.20

Plowshare’s first proposed venture, Project Chariot, aimed to excavate a harbor in northwestern Alaska. Deep historical detective work has exposed the secretive, hubristic ways in which Livermore’s scientist-administrators tried to exploit the Alaskan tundra for their own purposes, especially to sell the Central American sea-level canal and thereby keep the laboratory running while the U.S. observed a voluntary moratorium on nuclear weapons testing from 1958–61.21 Another theme of this literature is the rise of antinuclear environmental advocacy. In response to unexpected pushback from Indigenous people, local biologists, and citizen conservationists regarding radiation hazards, Teller and his Livermore associates sought to co-opt the opposition by sponsoring extensive bioenvironmental studies.22 However, rather than meeting AEC expectations, the AEC-funded University of Alaska biologists joined with grassroots allies to publicize both their pioneering research and their political arguments against the proposal.23

The Chariot studies and publicity had far-reaching effects. Barry Commoner, the biologist-activist and originator of the famous quote, “The first law of ecology is that everything is related to everything else,” traced his ecological awakening to the insight that Arctic lichen would absorb radioactive fallout from the atmosphere and contaminate the caribou grazing on them, in turn harming the human carnivores atop the tundra food chain.24 Moreover, the final official bioenvironmental report, which came out in 1966, four years after the AEC responded to the public uproar by canceling Chariot, has been hailed as a model for the first modern environmental impact statement.25

But getting to that point took much work and maneuvering by Chariot’s conflicting interests: “It was precisely through resistance to Plowshare program plans—and through Livermore’s strategies for overcoming resistances—that the environmental program took shape as it did.”26 Teller and his allies spent half a decade negotiating their high-modernist vision of plowsharing an instant harbor, and in the process wound up fostering new conceptions of progress, environmental and human health risk assessment, and planning in a high-tech society.27

That is not to say that such conceptions quickly transformed statist environmental management, nor that the AEC implemented such insights as it pursued PNE projects in other places over the next several years: “It was notoriously slow in learning lessons,” especially about overcoming public resistance to conducting experimental blasts outside the confines of the Nevada Test Site.28 Like others at the forefront of technological innovation, AEC and Plowshare administrators exhibited “uniqueness bias,” the tendency of planners to “see their projects as firsts, which impedes learning from other projects.”29 Despite the opposition of Alaskans to Project Chariot, a decade later the AEC persisted with an unpopular test in Colorado to investigate the feasibility of nuclear fracking. Although citizen environmentalists failed to prevent the detonation from taking place in October 1969, their groundbreaking lawsuit subjected the AEC to judicial review.30 The subsequent passage by Congress of the National Environmental Policy Act of 1969 (NEPA) provided Plowshare opponents with an even more potent legal instrument. By requiring federal infrastructure designers to conduct preliminary environmental impact studies, articulate less damaging alternatives, and solicit comments from the public, NEPA changed public works planning in the last three decades of the twentieth century in the United States, as well as in other democratic nations.31

NEPA and other environmentalist initiatives blunted the high-modernist and utilitarian rationales that had characterized the broader complex within which the AEC and other federal agencies operated to help citizens control nature. Historians of the environmental management state have begun to explicate how U.S. practices and policies designed to overcome environmental challenges functioned and evolved as part of a systematic enterprise of state building.32 Indeed, the Panama Canal itself constitutes a key case study of how U.S. officials solved complex environmental and public health problems by mobilizing science and technology on a scale comparable to waging war.33

Within six decades of the canal’s construction, however, state-sponsored environmental management underwent major transformations: from a confident, engineering-dominated enterprise in the heroic service of prosperity and modernity to a more ambiguous endeavor requiring recognition of uncertainty, sensitivity to multiple and nonelite stakeholders, consideration of alternatives, and suspicion of high-modernist technological solutions. By the 1970s, as knowledge of complex ecological consequences expanded and gained political legitimacy in democratic societies via laws like NEPA, civil engineers and hydro-engineers could no longer presume to exert the same levels of control as had their predecessors.34 Accordingly, addressing how statist environmental management policies and practices shifted over the middle decades of the twentieth century from conquering nature to implementing less damaging forms of development provides another rationale for paying attention to unrealized macroengineering projects and the debates they generated.

Toward this end, environmental historians have delineated several important controversial proposals beyond the realm of nuclear power that withered in the face of intense, sustained resistance. Recent studies of large-scale energy production and transportation plans that did not materialize during the 1960s and 1970s emphasize the skillful mobilization of scientific knowledge and new legal tactics by grassroots groups. U.S. environmentalists, often though not always allied with scientists, stopped the Storm King Mountain hydroelectric storage facility, designed to supply power for New York City; the Cross Florida Barge Canal, intended to provide a maritime shortcut across northern Florida; the completion of the Pan-American Highway through the Darién Gap of Panama and Colombia, a U.S. foreign aid project; and the U.S. supersonic transport aircraft program and associated Everglades Jetport, which was designed to be the world’s largest airport.35 Local environmentalist opposition and high costs also contributed to the early-1970s demise of Scripps Island, a planned underwater research facility on which the prestigious Scripps Institution of Oceanography spent almost a decade. Its downfall tells us much not only about how rapidly citizens in California and elsewhere redefined the appropriate use of marine and coastal resources, but also about changing scientific attitudes toward the practice and goals of oceanography.36

Other recent publications provide a rich foundation for rethinking unbuilt projects. Geographer Jonathan Peyton’s work on the history of unrealized development in a remote corner of British Columbia urges us to consider the “capacities that are created by failed schemes” and the “conditions of possibility” generated by such plans.37 How did the discourse related to development proposals—including the data produced to justify them—affect both the physical environment and human perceptions of it? Drawing upon decades’ worth of unsuccessful plans to industrialize the Stikine region of northwestern Canada, Peyton shows how such failures reinforced rather than weakened perceptions of the Stikine as a resource-rich landscape destined for development. Previous unsuccessful attempts to mobilize the area’s resources on a grand scale continue to exert influence on contemporary controversies regarding “the politics and possibilities of development” because they created things—paperwork, knowledge claims, memories, and physical landscape imprints such as geographical surveys—with which current stakeholders must reckon if they are to triumph in the latest round of debate. “The question is not why did something fail but, rather, what did failure produce, what kinds of effects did it have?” Examining what Peyton calls the multilayered side effects of unsuccessful development proposals accentuates the historical contingency of infrastructure project planning—past, present, and future.38

In a parallel vein, this book explores several multilayered effects that emerged over time as different U.S. actors invoked the isthmian sea-level canal proposal, and its exciting conditions of possibility, to solve different problems. For each of these contexts, it is useful to ask: What kinds of political and epistemic consequences did the proposal have, and what do they tell us about the changing political role of scientific expertise in the context of state-sponsored environmental management, especially regarding the concept of preliminary impact assessment? And how did unexpected obstacles posed by changing economic, political, and cultural climates, as well as the physical environment itself, alter the expectations and strategies of the proposal’s patrons? Addressing these questions invites us to interweave insights from multiple disciplines, especially diplomatic history and the environmental history of science, an approach that recognizes nature as an active shaper of scientific knowledge and institutions, not only as a passive subject of scientific inquiry.39

Seen through these lenses, the sea-level canal saga illuminates how geopolitical imperatives facilitated specific kinds of preproject field research in politically sensitive places, and in turn, how meteorological, geological, and other environmental constraints and discoveries subverted political and scientific expectations of how those landscapes could be developed. Collectively, the disparate phases of the failed seaway endeavor demonstrate how convergences of unforeseen political, economic, military, technological, scientific, and environmental forces sometimes stymied high-modernist plans, while also setting the stage for later iterations of the envisioned infrastructure.40

The first chapter of part I sets the scene by providing an alternative “shadow history” of the Panama Canal creation story that foregrounds the role of the sea-level design in the long quest to link the Atlantic and Pacific Oceans. Shadow histories utilize primary sources and other remnants of forgotten debates to remind us of visions of the future that once seemed possible.41 In this case, Ferdinand de Lesseps’s ruinous 1889 failure to cut all the way down across the isthmus should not eclipse the Euro-American scientific enthusiasm underpinning the endeavor. Indeed, the most famous scientist of the century, Alexander von Humboldt, who spent decades advocating for an artificial waterway, explicitly endorsed an interoceanic canal without obstructive locks in the 1850s.42 Moreover, for two years after the U.S. government resumed digging in 1904, arguments continued over whether to adopt the lock design that won out in the end.

Despite the triumphant opening of the lock canal in 1914, problems predicted by the sea-level advocates soon began to materialize. Chapters 2 and 3 address the growing technological obsolescence of the Panama Canal during the interwar years, the Atomic Age rationales and techniques for excavating a new waterway, the increasing Panamanian resistance against U.S. control of the Panama Canal and its colony-like enclave, and finally, the 1964 diplomatic crisis that led President Lyndon Johnson to announce that the United States would “plan in earnest” to replace the existing canal and renegotiate the inequitable 1903 treaty with Panama.43 For Johnson and his two predecessors, the sea-level canal offered a means of driving new discussions over decolonizing the Canal Zone while maintaining U.S. hegemony in the Western Hemisphere. In intriguing ways, the seaway proposal functioned as an instrument of both technological imperialism and the far rarer phenomenon of technological anti-imperialism.44

Part II transitions from the political opportunities that the nuclear canal idea provided for U.S. leaders to the preproject feasibility studies and ensuing debates. Focusing on the civilian presidential appointees of the Atlantic-Pacific Interoceanic Canal Study Commission, rather than Teller and the Livermore physicists, opens new interpretive pathways on the Panatomic Canal endeavor. The commissioners, whose backgrounds included law, engineering, administration, and the military, were enthusiastic about PNEs, but not blindly so. From 1965 to 1970 they oversaw a wide-ranging investigation, and when their final report recommended proceeding with sea-level canal construction using nonnuclear methods, critics across the political spectrum vilified them for wasting millions of dollars and minimizing scientific concerns about an emerging environmental issue: marine biological invasions. However, their declassified meeting transcripts reveal the flexibility with which the commissioners strove to complete their complicated mission, especially in the face of severe budgetary, meteorological, and time constraints and pressure from the scientific community that challenged their high-modernist tendencies. The commission’s work helps us appreciate the evolution of an adaptively technocratic form of preliminary environmental impact assessment in the transformative decade between Project Chariot and NEPA.

Toward this end, chapter 4 examines how the Canal Study Commission navigated a difficult course set by Congress and the president to determine the proposed waterway’s nuclear feasibility and optimal location. The commission’s workload included overseeing the collection of reams of economic, military, and engineering data and analyses of the seaway’s feasibility. At the same time, the chairman endeavored to persuade reluctant U.S. officials to allow the needed PNE experiments to take place at the Nevada Test Site, in spite of the risk of violating the Limited Nuclear Test Ban Treaty provision against cross-border radioactive debris. The commission chairman also led the 1964–67 initiative to renegotiate the 1903 treaty with Panama, a process in which the seaway proposal played a large part. Multiple diplomatic contingencies affected the scientific and engineering field studies, and vice versa.

Chapters 5 and 6 address how the commissioners dealt with scientific and political developments that destabilized the U.S. government’s high hopes for the proposed nuclear seaway. The engineering feasibility studies, which took place in the remote Darién portions of eastern Panama and northwestern Colombia, entailed numerous diplomatic and technical difficulties. The research teams struggled to complete their work in the contexts of the tropical climate, which limited operations to the four-month dry season, and the Vietnam War, which diverted needed funds, equipment, and personnel. The high-modernist dream of plowsharing the Darién collapsed in a literal and political quagmire.

A second set of challenges unfolded in a much more public way, as biologists associated with the Smithsonian Institution and several universities called for a share of the engineering feasibility funds to address the nonanthropocentric, nonterrestrial matter of marine species exchange. Ecological and evolutionary researchers raised concerns about the sea-level canal’s ability to allow sea snakes and other invasive organisms to cross between the Pacific and the Atlantic on a massive scale for the first time in approximately three million years. The issue led to heated debates between biologists and engineers about the oceans’ biological integrity, and among scientists about whether the megaproject represented a research opportunity or environmental threat. Biologists cannot take credit for stopping the nuclear canal, but they did contribute to new understandings of the areas of expertise considered relevant for assessing the environmental risks of maritime infrastructure.

Part III explores a subsequent side effect of the sea-level canal proposal, its nonnuclear revival by President Jimmy Carter as a solution to the 1970s-era oil crisis. An Alaskan senator convinced the president that a sea-level channel would facilitate the flow of North Slope oil to East Coast, Caribbean, and Gulf Coast refineries and thereby preclude the construction of expensive, disruptive new networks of terrestrial pipelines. As discussed in chapter 7, Carter confounded his environmentalist and diplomatic allies by insisting that the 1977 Panama Canal Treaty include a provision allowing a U.S. option for a new sea-level waterway. The last-minute addition created new kinds of work for the federal agencies required by NEPA to assess the sea-level canal’s likely environmental impacts. The treaty clause also rallied environmental advocacy groups, whose influence had grown significantly during the so-called environmental decade inaugurated by President Richard Nixon’s signing of the National Environmental Policy Act on January 1, 1970.

In this post-NEPA era, as addressed in chapter 8, the sea snake studies of the 1960s acquired a new political significance. Both conservative opponents of the Panama Canal Treaties and professionalized environmentalist organizations mobilized marine invasion ecology to discredit the seaway proposal. Moreover, the State Department incorporated scientific and political insights from the earlier canal ecology controversy into two remarkable documents: a groundbreaking environmental impact study of the 1977 pact granting Panama sovereignty over the waterway and surrounding enclave, and a statement of reassurance designed to win domestic environmentalist support for the treaty ratification campaign of 1978. This phase of the sea-level canal controversy signified the dissolution of the technocratic worldview that had underpinned the Panatomic proposal in favor of more democratic and precautionary modes of environmental governance.

The book concludes with a brief discussion of how Japanese interests revived the seaway idea in the 1980s for importing hydrocarbons and how more recent events link back to the feasibility studies of the late 1960s. By abrogating the 1903 accord, the 1977 canal treaties set the stage for a new diplomatic relationship in which Panama transitioned over the course of two decades toward assuming full responsibility for managing the waterway. The nation’s decision to modernize it by building a wider lane of locks from 2007 to 2016 drew in some ways on the ecological insights of the sea-level canal debates of the late 1960s and 1970s. Although environmentalists criticized Panama for not conducting a thorough, democratically informed environmental impact assessment, the canal now features a water-saving mechanism that has so far precluded the need to pump in seawater, which, as biologists warned over four decades ago, would eliminate a crucial freshwater barrier to marine species exchange.

Moreover, the biologists who put pressure on President Johnson’s Canal Study Commission set an example that has influenced recent scientific responses to the world’s largest planned infrastructural excavation project, the 170-mile-long Nicaragua Grand Canal.45 In 2014, the Nicaraguan government announced that construction had already begun, a year and a half after awarding the $40 billion concession to a Chinese business magnate eager to develop an alternative lock-based ship channel. Although the Nicaraguan government responded to protests by green-lighting an environmental and social impact assessment, a panel of international experts found it lacking. The country’s highest court dismissed the last environmentalist challenges in 2017, yet the project remains in limbo, a likely consequence of the Chinese concessionaire’s economic downfall as well as improved China-Panama relations. Like the Panama Canal expansion, the Nicaragua plan sheds light on how twenty-first-century Latin American nations weigh development priorities with post-NEPA concepts of statist environmental governance and public input procedures, especially in the context of the growing power of Asian energy and maritime shipping interests.

Ending with a yet-unrealized megaproject, especially one that embraces a resurgent form of high modernism, reiterates one of the book’s undercurrents: the idea that in order to come to fruition, large-scale infrastructure ventures require multiple forces—political, economic, technological, scientific, and environmental—to align in just the right way at just the right time. Tracing such developments, along with challenging entrenched assumptions about the inexorability of historical outcomes and notions of progress, is one of the most important jobs of the historian.

Choices by powerful interests have shaped every megaproject on Earth, but the longer such structures become a permanent part of the landscape, the harder it becomes to envision other conditions of possibility and alternative futures.46 To examine bygone debates over unbuilt projects reminds us of those multiple options, and of the negotiations required to bring large public works to fruition in democratic societies. For those now seeking to mitigate the threats to human rights and ecological quality posed by development plans, the sea-level canal story offers a hopeful precedent for challenging narratives of inevitability—but also an ominous reminder that environmental management, like nature itself, evolves along multiple, nonlinear paths and not necessarily toward progressive ends.