You’re standing in Key Largo, maybe grabbing a coffee at Mrs. Mac’s Kitchen, and you look at your phone. It says the distance from Key Largo to Key West Florida is about 98 miles. Easy, right? Two hours. Maybe less if you’ve got a lead foot.
But here’s the thing. The Overseas Highway is a liar.
The Overseas Highway, or U.S. 1, isn't your typical interstate. It’s a 113-mile chain of coral bedrock and concrete bridges that behaves more like a living organism than a road. If you treat it like a boring commute, you’re gonna have a bad time. You're basically driving across the ocean, and the ocean doesn't care about your schedule.
The Raw Math of the Miles
Let's talk numbers. From the heart of Key Largo (around Mile Marker 100) to the literal end of the road in Key West (Mile Marker 0), you are looking at roughly 97 to 100 miles.
It’s almost a straight shot south-southwest.
If you were in a vacuum, you'd be there in 90 minutes. But you aren't in a vacuum; you're in a subtropical paradise where the speed limit fluctuates between 35 and 55 mph like a heart monitor. The Florida Department of Transportation keeps a tight leash on those limits because, honestly, one wrong move and you’re in the Atlantic or the Gulf of Mexico. There’s no shoulder in some spots. Just water.
Traffic is the real kicker. During "season"—which basically runs from Christmas through Easter—that 98-mile stretch can take three hours. Sometimes four if a boat trailer decides to lose a wheel on the Seven Mile Bridge. You have to account for the "Florida Keys Crawl."
Why the Distance from Key Largo to Key West Florida Feels Longer (and Better)
Most people think of distance as a gap between two points. In the Keys, distance is measured in Mile Markers (MM). These little green signs are your lifeblood.
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Key Largo ends around MM 90. Then you hit Tavernier and Islamorada. By the time you reach the Middle Keys and Marathon at MM 50, you’ve covered half the distance from Key Largo to Key West Florida, but the scenery has completely shifted. You move from the dense hardwood hammocks of the Upper Keys to the wide-open, turquoise horizons of the Lower Keys.
The Seven Mile Bridge starts at MM 47.
Driving it feels like flying. It’s the longest bridge on the route, and it’s the psychological midpoint of the journey. Once you’re off that bridge, you’re in the "Real Keys." The air feels saltier. The vibe gets weirder.
The Islamorada Trap
You’ll probably stop in Islamorada. Everyone does. It’s about 15-20 miles into your trip. If you stop at Robbie’s Marina to feed the tarpon, you’ve just added an hour to your "distance." This is why people get frustrated. They see 100 miles on the map and think they can be in Key West for lunch. Then they see a 15-foot silver fish jumping for a bait bucket and suddenly they’re behind schedule.
Don't rush it. The distance is the point of the trip.
Realities of the Road: Construction and Deer
There is almost always construction. Because U.S. 1 is the only road in and out, any maintenance becomes a bottleneck. Local experts at the Monroe County Sheriff’s Office often warn that a single accident can shut down the entire highway for hours. There are no detours. You can't just "take a side street" when you’re on a bridge.
Then there are the Key Deer.
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Once you get down to Big Pine Key (around MM 30), the speed limit drops to 45 mph during the day and 35 mph at night. Strictly enforced. No jokes. These tiny, endangered deer are about the size of a large dog, and they have zero road sense. Hitting one is a tragedy and a massive fine. This stretch of the distance from Key Largo to Key West Florida is where your GPS usually fails to predict the slowdown.
The Bridges: A Quick List of What You’ll Cross
- Snake Creek Bridge: One of the few remaining drawbridges. If it’s up, you’re sitting for 10 minutes.
- Channel 2 and Channel 5 Bridges: Great spots where you’ll see people fishing off the old spans.
- The Seven Mile Bridge: The crown jewel. Don't take selfies while driving. Seriously.
- Bahia Honda Bridge: You’ll see the old, broken railway bridge standing next to the modern road. It looks like a post-apocalyptic movie set.
Fuel and Food: Strategic Planning
You don’t want to run out of gas in the middle of the Long Key Bridge. While gas stations are plentiful in Key Largo and Marathon, they get sparse in the stretches between.
Prices usually climb the further south you go.
If you're hungry, grab something in Marathon. It’s the last "big town" before the final 50-mile push into Key West. Once you pass the Seven Mile Bridge, the commercial density drops off significantly until you hit the outskirts of Stock Island.
When to Make the Drive
If you leave Key Largo at 8:00 AM on a Tuesday, you’re golden. You’ll cruise.
If you leave Key Largo at 3:00 PM on a Friday, you are joining a parade of every boat-trailer-towing tourist from Miami. The distance from Key Largo to Key West Florida doesn't change, but the "time-distance" triples.
Sundays are the reverse. Everyone is leaving Key West to go back to the mainland. If you’re heading south while everyone else is heading north, you’ll have a clear view of the misery on the other side of the road.
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Weather Factors
Florida weather is bipolar. A sudden afternoon squall can turn the Overseas Highway into a white-knuckle nightmare. Visibility drops to zero, and because you're surrounded by water, the wind can really buffeted your vehicle. If a hurricane or tropical storm is even thinking about coming near the coast, the Monroe County emergency management might implement one-way traffic patterns or mandatory evacuations. Always check the feed from @NWSKeyWest before you leave your hotel.
The Final Stretch: Entering Key West
The last 5 miles are the most confusing. As you cross the Cow Key Channel Bridge, U.S. 1 splits.
You have to choose: North Roosevelt Boulevard or South Roosevelt Boulevard.
North Roosevelt (to the right) is the commercial strip. It’s got the grocery stores, the traffic lights, and the "fastest" route to the historic district. South Roosevelt (to the left) is the scenic route. It takes you past Smathers Beach. It’s longer in terms of time, but it’s the ocean view you actually want.
If you’ve spent two hours staring at the tail lights of a Buick, take the South Roosevelt route. Smell the seaweed. It’s the proper way to finish the journey.
Actionable Advice for the Drive
To actually enjoy the distance from Key Largo to Key West Florida, you need a strategy that isn't just "follow Google Maps."
- Download Offline Maps: Cell service is mostly great, but there are weird dead zones over the longer bridges where the signal just disappears into the Gulf.
- Check the Wind: If winds are sustained above 25-30 mph, high-profile vehicles (RVs, vans) will struggle on the Seven Mile Bridge.
- The 10-Mile Rule: If you see a bathroom or a gas station and you’re at 50% capacity, stop. The "next" one might be 20 miles away and closed for renovations.
- Radio Check: Tune into 104.1 (US 1 Radio). They are the local authority on "The Stretch" and will tell you exactly where the cops are hiding and where the accidents are before Waze even figures it out.
- Hydrate: It sounds stupid, but the Florida sun through a windshield for two hours will dehydrate you faster than you think.
The trip is about 100 miles. It’s one road. It’s easy to navigate but hard to master. Stop thinking about the destination and just look out the window. By the time you hit the Southernmost Point buoy, you’ll realize the drive was the best part of the day.
Next Steps for Your Trip
- Check the Florida Keys 511 system for real-time traffic updates before leaving Key Largo.
- Verify your fuel levels in Marathon (MM 50) as it’s the last major stop for competitive gas prices.
- Plan your arrival for after 2:00 PM to avoid the morning "service vehicle" rush entering Key West.