- Where
- Monroe County, Florida
south-west from the peninsula - Coordinates
- 24.6667° N
81.3667° W - Biome
- Pine rockland, tropical hardwood hammock,
mangrove, seagrass and coral reef - The road
- Overseas Highway, US 1
113 miles, 42 bridges - Mile markers
- Count down from 126 to 0 at Key West
- The railway
- Built 1905–1912
Destroyed 2 September 1935 - Best visited
- December–April; hurricane season Jun–Nov
Drove a hundred miles of road laid across open sea, with an older bridge running alongside for most of it — sometimes carrying anglers, sometimes stopping abruptly in mid-air with the water going through the gap. Stopped at a small stone monument and read it properly, which took longer than I expected and was the right amount of time. Later a deer the size of a large dog walked out in front of the car and looked at me until I stopped.
The short answer
The Florida Keys are a chain of roughly 1,700 low limestone islands running south-west from the tip of Florida, of which about forty-five are linked by the Overseas Highway — 113 miles of road and forty-two bridges ending at Key West, ninety miles from Cuba. The route exists because Henry Flagler built a railway along it between 1905 and 1912, an undertaking called the eighth wonder of the world at the time. It operated for twenty-three years. The Labor Day Hurricane of 2 September 1935 — the first Category 5 storm recorded to make landfall in the United States — destroyed enough of the line that the railway sold the remains to the state for $640,000, and the Overseas Highway opened on the surviving structure in 1938.
Why it's worth knowing
Most road trips take you through a landscape. This one takes you along a ruin.
For most of the drive from Key Largo to Key West, a second bridge runs beside the one you are on. Sometimes it carries a fishing pier; sometimes it simply stops in open water with the sea running through the gap. These are Flagler’s. The concrete arches, the steel truss at Bahia Honda, the long viaduct at Long Key — all of it built before 1912 by men working from barges in a place with no fresh water, no shade and no way out when the weather turned.
The railway was not a folly in the end, although it was called one. It ran passenger trains to Key West for twenty-three years and connected the closest American deep-water port to a newly opened Panama Canal. What killed it was a single night.
And the way it died is the part that matters. In 1935 several hundred unemployed veterans of the First World War — men from the Bonus Army, given Depression-era work building the highway’s bridges — were housed in camps on Windley Key and Lower Matecumbe. When the hurricane came, a rescue train was sent down the line for them. It arrived late and was thrown from the tracks at Islamorada by a storm surge estimated at eighteen to twenty feet.
Reported death tolls vary between roughly 400 and 500, of whom something over 250 were veterans. Ernest Hemingway, who lived in Key West and went up to help with the bodies, wrote a furious piece about who had sent them there and why. A monument at mile marker 82 in Islamorada, unveiled in 1937, holds the ashes of victims cremated on pyres after the storm.
So the drive is not just scenic. Every one of those disused bridges was built by someone, and one of the reasons the road exists is that a great many of them died.
The field notes
Key Largo — the reef, and the first of its kind
The chain begins at mile marker 106. Key Largo is the longest of the Keys and its interest is almost entirely underwater: this is the northern end of the only living coral barrier reef in the continental United States.
John Pennekamp Coral Reef State Park, dedicated in 1963, was the first undersea park in the United States — an idea that had to be invented, since protecting a place nobody could stand on had no precedent. It is now bordered by the far larger Florida Keys National Marine Sanctuary, designated in 1990, which covers thousands of square miles of reef, seagrass and mangrove.
The reef is in serious difficulty. Coral cover has declined steeply over decades from disease, warming and water quality, and the marine heatwave of 2023 caused severe bleaching across the Keys. Restoration nurseries now grow and outplant coral along the tract. It is an active conservation effort rather than a settled success, and any account that describes the reef as it was in 1970 is describing something that has changed.
Islamorada — the monument at mile 82
Islamorada calls itself the sport fishing capital of the world and the claim is at least defensible: the Atlantic drops off steeply here and the flats on the bay side are among the best-known bonefish and tarpon grounds anywhere.
It is also where the 1935 storm came ashore hardest. The eye passed over Lower Matecumbe and Long Key. Most buildings in Islamorada were flattened, and the workers’ camps were simply gone.
The Hurricane Monument stands at mile marker 82, a coral-rock memorial unveiled in 1937 before a crowd of around four thousand, with a crypt in front holding victims’ ashes. It was added to the National Register of Historic Places in 1995 and is maintained in part by descendants of the dead. It takes ten minutes to stop. It is the most important ten minutes on the drive.
Marathon, Pigeon Key and the Seven Mile Bridge
Marathon is the middle of the chain and its name is said to come from the pace of the railway construction. Just west of it the Seven Mile Bridge crosses the widest open water on the route — in fact a little under seven miles.
Beneath the old bridge sits Pigeon Key, a five-acre island that housed the men who built and then maintained this section. Its buildings survive, and it has now been abandoned twice: once after 1935, and again in 1982, when the new bridge opened a few hundred metres away and left the island with no road to it.
A stretch of the old Seven Mile Bridge has been restored and reopened as a walking and cycling route to Pigeon Key, which is the best way in the Keys to stand on Flagler’s structure and understand what building it involved.
Bahia Honda — the bridge they put a road on top of
The single most striking piece of engineering on the route is at Bahia Honda, and the reason is a mistake nobody could have anticipated.
The water here is unusually deep, so the engineers abandoned the concrete arches used elsewhere and built a steel truss instead. When the state converted the railway to a highway after 1935, it found the deck inside the truss was too narrow for cars.
So they built the road on top. The highway ran along the upper chord of a railway bridge, high above the water, with no shoulder and a view that motorists in the 1930s found genuinely alarming.
A four-lane replacement opened in 1972 a few hundred yards north, and two spans of the old bridge were removed — partly for boat traffic, partly to stop people walking out onto it. What remains is a steel truss standing in open water with a road surface on its roof, stopping abruptly in mid-air. It is the best-known image in the Keys and it is a photograph of a solved problem.
Bahia Honda State Park around it has what is generally reckoned the finest natural beach in the Keys, which in an archipelago built of coral rock is rarer than it sounds.
Big Pine Key — fresh water, and a deer the size of a dog
Big Pine is a geological accident. The Keys have almost no fresh surface water, but the karst limestone here holds rainwater in a lens beneath the island, and Blue Hole — a flooded quarry — is the largest body of fresh water in the chain.
That water supports the Key deer, Odocoileus virginianus clavium, the smallest subspecies of white-tailed deer in North America. A grown buck stands no taller than a German shepherd. They exist nowhere else, they swim between islands, and their range now runs roughly from Big Pine to Sugarloaf, with around seventy-five per cent of the population on Big Pine and No Name Keys.
The recovery is real and precarious. Hunting and habitat loss took the population below fifty by the mid-twentieth century; published figures for the low point differ, and the National Key Deer Refuge was established in 1957. Numbers now run at roughly 700 to 800, with some accounts saying nearly a thousand. It has been federally endangered since 1967.
Three modern threats, in order of body count. Cars account for around half of all deaths — US 1 runs straight through the refuge. Screwworm: an outbreak of the New World screwworm in 2016 killed at least 127 to 135 deer, most of them adult males infected through sparring wounds, and was halted by the release of sterile flies. And Hurricane Irma passed directly over the herd as a Category 4 in 2017, with mortality estimated in a range so wide — 38 to 68 per cent — that it is really a statement of how hard the herd is to count.
The deer are also being domesticated by kindness. Big Pine had 500 residents in 1968 and has more than 5,000 now, and illegal feeding has produced animals that approach slow cars for handouts. Feeding them is the single most harmful thing a visitor can do here.
Key West — mile marker zero
The road ends at Key West, which is closer to Havana than to Miami and has never entirely accepted being part of anywhere.
It was for a time the largest and wealthiest city in Florida, built on wrecking — salvaging ships off the reef — then sponging and cigars, and it has been a naval town, a bankrupt town in the 1930s, and a refuge for writers. Hemingway’s house on Whitehead Street is a museum, complete with the descendants of his cats.
In 1982 the US Border Patrol set up a roadblock at Florida City and searched every vehicle leaving the Keys, which produced a traffic queue nineteen miles long and destroyed the tourist season. Key West responded by declaring independence as the Conch Republic, symbolically seceding, briefly declaring war, and immediately applying for foreign aid. The roadblock came down. The republic has never quite been dissolved, and its flag is everywhere.
The sunset gathering at Mallory Square, the southernmost point marker, Duval Street at night: all of it is well-known, crowded and worth doing once. The better hours here are early morning, when the town is quiet and the light comes off the water.
- Do not drive it in one go. That is not the trip.
- Stop at mile marker 82 and read the monument.
- Walk out onto the old Seven Mile Bridge to Pigeon Key.
- Look up at Bahia Honda and work out what they did there.
- On Big Pine, drive slowly and do not feed anything.
A bridge that stops. Along most of the drive a second, older bridge runs alongside the road, and in several places it simply ends in mid-air where a span was removed — concrete and steel reaching out over open water and then not. It is the most ordinary sight in the Keys. Every one of those structures was laid by hand from a barge before 1912, and the road you are on is only there because they were.
Tally, in the marginConcrete and steel reaching out over the water and then simply stopping. Somebody laid every one of those by hand from a barge, and the road I am on is only here because they did.
Getting there
How to get there. One road: US 1, the Overseas Highway, running 113 miles from Florida City to Key West. Miami is about an hour from the start of it and roughly four hours from the end, traffic permitting, which it frequently does not. Key West has an international airport with connections through Miami, Fort Lauderdale, Atlanta and Charlotte, and there is a passenger ferry from Fort Myers and Marco Island.
The mile markers are the address system. Green signs count down from MM 126 at Florida City to MM 0 in Key West, and everything — hotels, restaurants, dive shops, the hurricane monument — is located by marker rather than by street. Learn to read them and the whole chain becomes navigable.
Do not drive it in a day. The distance is trivial and the point is the stopping: Pennekamp at MM 102, the monument at MM 82, Pigeon Key and the old Seven Mile Bridge at MM 47, Bahia Honda at MM 37, the deer refuge at MM 30. Two or three nights spread along the chain is the difference between seeing the Keys and driving past them.
When to go. December to April is the dry season: warm, low humidity, and busy enough that accommodation should be booked well ahead. Summer is hot, wet and cheaper. Hurricane season runs June to November, peaking August to October — storms are forecast days ahead and evacuation orders for the Keys are issued early and taken seriously, because there is one road out.
On Big Pine, slow down. Speed limits through the refuge are lower than elsewhere and enforced, and roughly half of all Key deer deaths are vehicle collisions. Drive the posted limit at night. Do not feed them, however much they ask.
On the reef, use reef-safe sunscreen, do not touch or stand on coral, and use mooring buoys rather than anchoring. The reef is under active restoration and visitor behaviour is a live variable rather than a formality.
Mark this place
Common questions
What was the Overseas Railroad?
An extension of Henry Flagler’s Florida East Coast Railway from the mainland to Key West, built between 1905 and 1912 across open water and called the eighth wonder of the world. It carried passengers for twenty-three years until the Labor Day Hurricane of 1935 destroyed much of the line. The railway sold the remains to the state of Florida for $640,000, and the Overseas Highway opened on the surviving structure in 1938.
What happened in the 1935 Labor Day Hurricane?
A Category 5 hurricane — the first recorded to make landfall in the United States — struck the Upper and Middle Keys on 2 September 1935, with a storm surge estimated at 18 to 20 feet. It destroyed the railway and levelled most buildings in Islamorada. Hundreds of First World War veterans working on highway construction were housed in camps in its path; a rescue train sent for them arrived late and was derailed. Reported death tolls range from roughly 400 to 500.
Why does the old Bahia Honda bridge have a road on top of it?
Because the water there was too deep for the concrete arches used elsewhere, so the railway used a steel truss instead — and when the state converted the line to a highway after 1935, the deck inside the truss proved too narrow for cars. Rather than rebuild, engineers laid the road along the top of the structure. A replacement bridge opened in 1972 and two spans of the old one were later removed.
What is a Key deer?
The Key deer (Odocoileus virginianus clavium) is the smallest subspecies of white-tailed deer in North America and exists only in the Florida Keys. A grown buck stands roughly the height of a German shepherd. The population is concentrated on Big Pine and No Name Keys, which hold about seventy-five per cent of the total, and the species has been federally endangered since 1967.
How many Key deer are there?
Estimates cluster between 700 and 800 according to the Florida Fish and Wildlife Conservation Commission, with some accounts giving close to a thousand. Numbers fell below fifty in the mid-twentieth century before the National Key Deer Refuge was established in 1957. A screwworm outbreak in 2016 killed at least 127 to 135 animals, and Hurricane Irma in 2017 caused losses estimated between 38 and 68 per cent.
What is the best beach in the Florida Keys?
Bahia Honda State Park at mile marker 37 is generally regarded as having the finest natural beach in the chain. That distinction matters more than it sounds: most of the Keys are coral rock rather than sand, and many of the region’s beaches are imported or engineered.
What is the Conch Republic?
A secession declared by Key West in 1982 in protest at a US Border Patrol roadblock that searched every vehicle leaving the Keys and created a traffic queue nineteen miles long. Key West symbolically seceded, briefly declared war, and immediately applied for foreign aid. The roadblock was removed. The republic has never quite been dissolved and its flag is displayed throughout the town.
Is the Florida Keys reef still alive?
It survives and it is in serious difficulty. This is the only living coral barrier reef in the continental United States, protected within the Florida Keys National Marine Sanctuary since 1990, but coral cover has declined steeply over decades from disease, warming and water quality, and the marine heatwave of 2023 caused severe bleaching. Restoration nurseries now grow and outplant coral along the reef tract.
How long does it take to drive the Overseas Highway?
About four hours from Miami to Key West without stopping, and that is the wrong way to do it. The interest is in the stops: Pennekamp at MM 102, the Hurricane Monument at MM 82, Pigeon Key and the old Seven Mile Bridge at MM 47, Bahia Honda at MM 37 and the deer refuge at MM 30. Two or three nights spread along the chain is a better plan than a day’s drive.