So, you're planning that bucket-list drive down U.S. 1. You've probably seen the drone footage of a car seemingly floating over turquoise water and wondered, "Wait, how long is bridge to key west anyway?"
It’s a fair question. Honestly, it’s also a confusing one because there isn’t just one bridge.
The Overseas Highway is basically a 113-mile-long game of island-hopping. You aren't just crossing one giant span; you’re traversing a massive network of 42 different bridges. If you’re looking for the "big one"—the legendary Seven Mile Bridge—it’s actually 6.79 miles long. Yeah, they rounded up. But when you’re suspended over the Moser Channel with nothing but salt air and the Gulf of Mexico on one side and the Atlantic on the other, those missing 0.21 miles really don't matter.
The Big One: Seven Mile Bridge Explained
When people ask how long is bridge to key west, they almost always mean the Seven Mile Bridge. Located at Mile Marker 47 near Marathon, it’s the undisputed heavyweight champion of the Florida Keys.
Built between 1978 and 1982, this modern concrete marvel replaced the original railroad bridge built by Henry Flagler. The "New Seven," as locals sometimes call it, is a box-girder structure that rises 65 feet at its highest point. Why so high? To let the sailboats through, obviously. It’s wide enough to feel safe, but long enough that if you have a fear of bridges (gephyrophobia is real, folks), your knuckles might get a little white.
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The Old Seven vs. The New Seven
You’ll notice a second, rusting bridge running parallel to the highway. That’s the "Old Seven."
- Old Seven Mile Bridge: Completed in 1912 for Flagler’s Over-Sea Railroad. It was a terrifyingly narrow two-lane road for decades until the new one opened.
- The Gap: You might see a chunk missing from the old bridge. That wasn't an accident. They removed sections to prevent people from driving on the old, decaying structure and to allow taller ships to pass without needing a drawbridge.
- Pigeon Key: About 2.2 miles into the old bridge (from the Marathon side), you'll see a tiny island. That’s Pigeon Key. It used to be the base camp for the railroad workers. Today, you can actually walk or take a tram across the renovated section of the old bridge to visit the island.
Beyond the Seven Miles: The 42-Bridge Count
It’s easy to focus on the long one, but the journey to Key West starts way before Marathon. From the moment you leave the mainland at Florida City, you’re entering a world where road and water blur.
Total bridge distance? About 18.8 miles of your trip is spent entirely over water.
Jewfish Creek Bridge is your first real taste of the "high life" at Mile Marker 106. It’s about 1.25 miles long and serves as the gateway to Key Largo. Then you’ve got the Long Key Bridge, which stretches for 2.3 miles. It’s much lower to the water and feels more like you’re skimming the surface.
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Then there’s the Bahia Honda Bridge. If you want the best photo op of the whole trip, this is it. The old railroad bridge here sits high above the water, looking like a giant skeleton of Florida’s industrial past. The new highway bridge runs right next to it, offering a panoramic view of Bahia Honda State Park, which—unpopular opinion—has better beaches than Key West itself.
How Long Does the Drive Actually Take?
Distance is one thing. Time is another.
If you drive from Miami to Key West without stopping (which is a crime, honestly), it’ll take you about 3.5 to 4 hours. But traffic in the Keys is a temperamental beast.
- The One-Lane Struggle: Most of the Overseas Highway is a two-lane road. If someone is driving 10 mph under the limit to look at a manatee, everyone is driving 10 mph under the limit.
- Weekend Rush: Friday afternoons heading south and Sunday afternoons heading north are brutal. Plan accordingly.
- Mile Markers: In the Keys, we don't use addresses. We use Mile Markers (MM). Key West is MM 0. Key Largo is roughly MM 100. If someone says, "Meet me at the taco stand at MM 82," just look for the little green signs on the side of the road.
Surprising Facts About the Journey
There’s a tree growing out of the old bridge. No, seriously.
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Locals call it "Fred the Tree." It’s an Australian Pine that somehow took root in the middle of the old, abandoned Seven Mile Bridge. People decorate it for the holidays. It’s survived multiple hurricanes, which is more than most of the patio furniture in Marathon can say.
Also, the bridge system isn't just for cars. It carries a massive freshwater pipeline from the mainland. Key West doesn't have its own fresh water, so every sip of water you take at a bar on Duval Street traveled over those 42 bridges just like you did.
Is it Worth the Drive?
Kinda? No, it’s definitely worth it.
The Seven Mile Bridge is more than just a piece of infrastructure. It’s a transition. Once you cross it, you’re officially in the "Lower Keys." The vibe changes. It gets quieter, the water gets clearer, and the "Conch Republic" lifestyle starts to make sense.
If you're worried about how long is bridge to key west because you’re nervous about the drive, don’t be. The modern bridges are incredibly sturdy—built to withstand 200 mph hurricane winds. They’re wide, well-maintained, and honestly, the views are so distracting you’ll forget you’re miles away from land.
Actionable Advice for Your Trip
- Check the Wind: If winds are sustained over 35-40 mph, high-profile vehicles (RVs, vans) can feel a bit "sway-y" on the Seven Mile Bridge.
- Stop at Pigeon Key: Park at the Marathon end of the Seven Mile Bridge and walk the 2.2 miles of the "Old Seven" for sunset. It’s the best view in the state.
- Fuel Up Early: Gas gets more expensive the closer you get to Key West. Fill up in Florida City or Key Largo to save a few bucks.
- Download an Offline Map: Cell service is usually fine, but there are "dead zones" over the longer stretches of water where your GPS might get confused.