Overseas Highway Road Trip Guide
Start: Florida City / Key Largo (US 1 leaves the mainland near MM 126). End: Key West, MM 0 at the corner of Whitehead and Fleming Streets. · About 113 miles along US 1, from Mile Marker 126 in Florida City down to Mile Marker 0 in Key West.
Route at a Glance
Distance
About 113 miles along US 1, from Mile Marker 126 in Florida City down to Mile Marker 0 in Key West.
Drive time
Roughly 3 to 3.5 hours non-stop; plan 2 days to actually stop and snorkel, swim, and eat.
Route
Start: Florida City / Key Largo (US 1 leaves the mainland near MM 126). End: Key West, MM 0 at the corner of Whitehead and Fleming Streets.
Which way to drive
Drive north-to-south (Florida City toward Key West). Mile markers count down to MM 0 at Key West, so southbound you are heading toward the finish line. The longest water crossing, the Seven Mile Bridge, sits roughly mid-route just past Marathon.
About the Overseas Highway Drive
The Overseas Highway (US Route 1 through the Florida Keys) runs 113 miles from Florida City to Key West across 42 bridges and more than 30 islands. Built on the roadbed of Henry Flagler's Overseas Railroad (destroyed by the 1935 Labor Day Hurricane), the highway crosses the Atlantic Ocean and the Gulf of Mexico simultaneously. The Seven Mile Bridge (mile marker 40) is the showpiece — 6.79 miles of concrete spanning open water with the old Flagler railroad bridge running parallel. Mile markers count down from 127 (Florida City) to 0 (Key West). Key Largo (mile marker 100) is the dive capital with John Pennekamp Coral Reef State Park. Islamorada (mile marker 80) is the sportfishing capital. Marathon (mile marker 50) is the midpoint with the Turtle Hospital. Big Pine Key (mile marker 30) has the Key deer — the smallest deer in North America.
Free Overseas Highway Audio Road Trip Guide with Roamee Pro
Roamee Pro offers a free GPS audio guide for the Overseas Highway drive. Stories play automatically as you reach each stop — Seven Mile Bridge (mile marker 40), Bahia Honda State Park (mile marker 37), John Pennekamp Coral Reef State Park (mile marker 102.5) — so you keep your eyes on the road. Works offline.
explore by interest
Major Stops Along the Route
- 1Key Largo (MM 106-90) — John Pennekamp Coral Reef State Park at MM 102.5 is the first undersea park in the United States; glass-bottom boat and snorkel trips to the reef depart here.
- 2Islamorada (MM 90-72) — Sportfishing center; Theater of the Sea (MM 84.5) and Robbie's of Islamorada (MM 77.5), where you can hand-feed the tarpon.
- 3Marathon (MM 53-47) — Roughly the halfway point. Crane Point Museum and the Turtle Hospital (MM 48.5, tours by reservation). Refuel here before the long bridges.
- 4Seven Mile Bridge / Pigeon Key (MM 47-40) — One of the longest open-water segments; the old parallel bridge leads to historic Pigeon Key, a former rail-construction camp.
- 5Bahia Honda State Park (MM 37) — Calusa and Loggerhead beaches; walk the old Flagler railway bridge section for an elevated view.
- 6Big Pine Key (MM 33-30) — National Key Deer Refuge; the endangered Key deer are small and cross the road. Reduced night speed limits are enforced.
- 7Key West (MM 4-0) — Endpoint. Mallory Square sunset, the Hemingway Home (907 Whitehead St), and the Southernmost Point buoy, about 90 miles from Cuba.
Don't-Miss Sights Along Overseas Highway
- •Seven Mile Bridge (mile marker 40) — a 6.79-mile bridge across open ocean with the parallel ruins of the 1912 Flagler railroad bridge beside it
- •Bahia Honda State Park (mile marker 37) — a barrier island with one of the top-rated beaches in the United States and the ruins of the old Overseas Railroad bridge
- •John Pennekamp Coral Reef State Park (mile marker 102.5) — America's first undersea park with glass-bottom boat tours and snorkeling on the only living coral barrier reef in the continental US
- •Key West — mile marker 0, the southernmost point of the continental US, with Duval Street, Hemingway's house, and sunset celebrations at Mallory Square
Best Viewpoints
- •Seven Mile Bridge over open water between Marathon and Little Duck Key
- •Old Pigeon Key bridge section, looking back along the original Overseas Railroad
- •Bahia Honda old railway bridge overlook at MM 37
- •Anne's Beach boardwalk, Lower Matecumbe Key (MM 73)
- •Southernmost Point buoy, Key West
Worthwhile Detours off Overseas Highway
- •Old Seven Mile Bridge — the original 1912 Flagler railroad bridge, now open as a pedestrian path extending 2.2 miles into open water from the Marathon side
- •No Name Key — an unpopulated island accessible by bridge from Big Pine Key where endangered Key deer wander freely and the road dead-ends at a boat ramp with no services
Fuel, Food & Services
Gas and food are continuous through Key Largo, Islamorada, and Marathon, but thin out south of Marathon. Fill the tank in Marathon (around MM 50) before the Seven Mile Bridge; the next reliable cluster of stations and restaurants is Big Pine Key (MM 30) and then Key West. Prices in the Keys run higher than on the mainland.
Road Conditions
Mostly flat, two-lane US 1 at sea level with no grades, tunnels, or hairpins; the challenge is traffic, not terrain. The route crosses 42 bridges, including the 7-mile span. Cell coverage is generally good in the towns but can drop on the longer bridges. Expect congestion behind slow traffic, with limited passing zones. Watch for Key deer crossing on Big Pine Key, especially at dawn and dusk.
Best Season to Drive
December through April (dry season) has the lowest rain and humidity and the best diving visibility. Hurricane season runs June 1 to November 30, with September and October the peak risk; storms can force evacuations and close US 1, the only road in or out. Summer is hot, humid, and buggy. (Note: there are no mountain-pass seasonal closures here, as US 1 is at sea level.)
RVs & Trailers
Fully RV- and trailer-friendly: flat, with no grades, tunnels, or vehicle-size limits on US 1. High winds can be a factor for tall rigs on the Seven Mile Bridge. State park campgrounds (Bahia Honda, John Pennekamp) book months ahead, so reserve early.
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