Florida began building what was intended to become the world's largest airport on 39 square miles of swamp beside the Everglades, five times the size of JFK and linked to both coasts by highway and high-speed transit — only one runway was finished, and the surrounding land became Big Cypress National Preserve

An hour west of Miami, the sawgrass parts to reveal 10,500 feet of immaculate concrete lying in the middle of a swamp. No terminal. No baggage hall. No queue for overpriced coffee. Just a runway, a parallel taxiway, and an alligator population that has never once been asked to produce a boarding pass.

That strip is all that got built of what was meant to be the biggest airport on Earth.

What the jetport was supposed to be

Florida in the mid-1960s was growing fast, and Miami’s planners answered with a scheme that reads today like a fever dream with a budget attached. Supersonic passenger jets were assumed to be the obvious next step in aviation, and since nobody wanted sonic booms rattling crockery over a crowded city, the new airport had to go somewhere nobody lived. Dade County Port Authority settled on 39 square miles of Big Cypress Swamp, some 24,960 acres, six miles north of the Everglades National Park boundary.

According to the National Park Service, the design called for six runways and a corridor 1,000 feet wide running out to both Florida coasts, carrying a new interstate highway and a monorail. Planners spoke about aircraft carrying up to 1,000 passengers apiece. Finished, the complex would have been five times the size of JFK in New York.

Ground broke in September 1968. The Miami News covered the ceremony at the time, and its account was revisited decades later by the Marco Eagle: bulldozers splashing through wet ground, crews spreading fill and wood shavings over the mud, puddles seeping through anyway. Someone set off a dynamite blast in the distance for the cameras.

The report that turned it around

“Inexorably destroy the south Florida ecosystem.”

That was the opening verdict of the environmental impact study commissioned by the Interior Department and directed by Luna Leopold, a senior hydrologist with the US Geological Survey and son of the conservationist Aldo Leopold. Working alongside the ecologist Arthur Marshall and Manuel Morris of the National Park Service, Leopold argued that the airport itself was almost beside the point. Damage would come from everything that followed it. Drainage, highways, housing, agriculture, hotels, all of it radiating out from a facility that needed tens of thousands of workers, and workers who needed somewhere to live.

Released in 1969, the study is generally credited as the first of its kind conducted in Florida, and it arrived before the National Environmental Policy Act existed to require such a thing. One report, on one project, by three men who were openly opposed to it. What it supplied was numbers, and the opposition used every one of them.

A one-dollar membership and a pair of dark glasses

Marjory Stoneman Douglas was 79 years old, losing her sight, and had already written the book that taught America to call the Everglades a river of grass. Asked to help fight the jetport, she said she would do whatever she could. In 1969 she founded Friends of the Everglades, set annual dues at one dollar, and signed up as its first member.

Then she went to work. The National Women’s History Museum records that she served as the organisation’s first president and toured Florida giving speeches against the project. Membership passed 3,000 within a few years, drawn from dozens of states.

She had unlikely company. Hunters, Miccosukee and Seminole families, off-road vehicle enthusiasts and conservation groups all arrived at the same position from wildly different directions, which is not a coalition any lobbyist would have drawn up on purpose.

Construction stopped in 1970 under an agreement known as the Everglades Jetport Pact. One runway had been finished. The remaining five were never begun.

What the swamp got instead

So what do you do with 700,000 acres of wetland that a lot of people have just agreed to protect for completely incompatible reasons?

Congress invented a category. On 11 October 1974, President Gerald Ford signed Big Cypress into existence as the first national preserve in the country. The designation protects the watershed while still permitting hunting, off-road vehicles, oil and gas extraction, cattle grazing and traditional use by the Seminole and Miccosukee. A national park would have locked those uses out, and the deal would have collapsed.

The airstrip survived, renamed the Dade-Collier Training and Transition Airport, and spent decades as a place for airline pilots to practise touch-and-goes in the dark with nobody underneath to annoy. Pan Am and Eastern were regulars. Its manager told CNN in 2022 that visitors often assume the field is abandoned, which it is not, though these days it keeps office hours.

Recent years have been stranger. Florida took over the site in 2025 for an immigration detention camp, which closed in June 2026. Miami-Dade County announced in August that it had formally regained control of the property and was documenting damage to the airfield and the surrounding land.

Leopold’s report was a single study rather than a scientific consensus, and it was written to answer one narrow question about one proposed airport. It has aged extraordinarily well anyway, largely because the thing it warned about kept coming back in new clothes. The fight it started, over what a swamp is worth and who gets to decide, has never really finished.